What kind of new models to expect from the big names.

[PR19_Kit]

With that printer costing £2500 + you could sub-contract a LOT of decals to a professional company for less. 

In any case, how do you tell the printer NOT to print white over all the bits of the artwork that are clear, but look white on the .bmp file or whatever?

[jcf]

All of the "white ink" printers on the market are sublimation printers.

Epson have been selling their Ultrachrome white ink for their top-range inkjets for several years now. Their current model is the SureColor SC-V7000.
There is also the Ghost white toner for laser printers.

The machines and inks are very expensive

Quite so. You have nailed the reason they would need to come down in price.

The only white printers they offer are DTF (Direct to Film) for heat transfers, and DTG (Direct to Garment) which prints directly onto specially treated fabric which then has to go through a drying process. The printers are $19,000.
They were selling direct print to hard material printers - wood, metal, foamcore, expanded PVC sheet etc. One was aimed at the sign production segment, the other was primarily for creating printing plates. But they've been discontinued.

None of them are designed to print on regular paper or decal paper, nor could they as the
heavily pigmented white ink wouldn't work
very well with regular consumer desktop
printers. The white cartridges and the nozzles
of the tank printers evidently clog and fail
more than the other colours.

[steelpillow]

The only white printers they offer are DTF (Direct to Film) for heat transfers, and DTG (Direct to Garment) which prints directly onto specially treated fabric which then has to go through a drying process. The printers are $19,000.
They were selling direct print to hard material printers - wood, metal, foamcore, expanded PVC sheet etc. One was aimed at the sign production segment, the other was primarily for creating printing plates. But they've been discontinued.

None of them are designed to print on regular paper or decal paper, nor could they as the
heavily pigmented white ink wouldn't work
very well with regular consumer desktop
printers. The white cartridges and the nozzles
of the tank printers evidently clog and fail
more than the other colours.

Really? To quote from the User Guide: "The Epson SureColor SC-V7000 is also compatible with a range of media, including rolls of paper, banners and fabric, making it a versatile printing solution for various industries."
No doubt that suggests expensive coated papers, but I see no reason to exclude decal sheet. It'll even top off with a coat of varnish, so you don't need to cut them out precisely.
Granted it says you have to tape small sheets down to stop them warping under the UV lamp.

They used to sell the Stylus Pro WT7900 which did "Fine Art, Roll Paper, Thick Media Support", dunno why they withdrew it. Can still find the white ink cartridges.

[Hobbes]

With that printer costing £2500 + you could sub-contract a LOT of decals to a professional company for less. 

In any case, how do you tell the printer NOT to print white over all the bits of the artwork that are clear, but look white on the .bmp file or whatever?

When you use a file format that supports transparency (for example, PNG), you can make the parts of the image that are intended to be transparent actually transparent. Graphics programs generally indicate this by giving the transparent area a checkerboard pattern instead of making it white.
This means the white areas and the transparent areas have different colors, and the printer will not print anything on the transparent areas.

[PR19_Kit]

When you use a file format that supports transparency (for example, PNG), you can make the parts of the image that are intended to be transparent actually transparent. Graphics programs generally indicate this by giving the transparent area a checkerboard pattern instead of making it white.
This means the white areas and the transparent areas have different colors, and the printer will not print anything on the transparent areas.

Ah, I didn't know that, thanks.

I've never used .png files before, I'll give it a go maybe.

[jcf]

The only white printers they offer are DTF (Direct to Film) for heat transfers, and DTG (Direct to Garment) which prints directly onto specially treated fabric which then has to go through a drying process. The printers are $19,000.
They were selling direct print to hard material printers - wood, metal, foamcore, expanded PVC sheet etc. One was aimed at the sign production segment, the other was primarily for creating printing plates. But they've been discontinued.

None of them are designed to print on regular paper or decal paper, nor could they as the
heavily

 pigmented white ink wouldn't work
very well with regular consumer desktop
printers. The white cartridges and the nozzles
of the tank printers evidently clog and fail
more than the other colours.

Really? To quote from the User Guide: "The Epson SureColor SC-V7000 is also compatible with a range of media, including rolls of paper, banners and fabric, making it a versatile printing solution for various industries."
No doubt that suggests expensive coated papers, but I see no reason to exclude decal sheet. It'll even top off with a coat of varnish, so you don't need to cut them out precisely.
Granted it says you have to tape small sheets down to stop them warping under the UV lamp.

They used to sell the Stylus Pro WT7900 which did "Fine Art, Roll Paper, Thick Media Support", dunno why they withdrew it. Can still find the white ink cartridges.

Yeah, and the V7000 is an $84,000 flatbed
with a 1.25 X 2.5 meter vacuum deck.

The WT7900 was specifically designed to produce printing plates.

None of these machines would be used for
what you're talking about, you could set up
a screenprinting business to produce decals
with less of an investment.