Need to Print in Silver Metallic or White on Envelopes

So, as the title says, I'm looking for a printer that will print addresses, postage, and USPS barcodes onto A9 (5.75"x8.75") envelopes in either silver or white color. The envelopes are made from a special metallic blue paper (http://gruppocordenons-usa.com/fine-paper/sosilk-fsc/), thus dark ink won't contrast enough to meet the postal service requirements. We'd like to avoid using labels, as we want the envelopes to look as clean and professional as possible... Especially considering that we'd need 4 separate labels (to address, return address, intelligent barcode, and postage).

I was considering purchasing an Alps printer on eBay (MD-5000, or MD-5500), but I've heard that the ink is a wax based fragile material that would likely rub off or be damaged when the USPS handles it. I'm aware that there's other similar printers from Citizen, OKI, Kodak, Roland, Powis Parker, Kimoto, but I have no idea if these would work for us or not.

I'm open to the idea of using inkjet technology, but I'm not sure which printers currently offer this.

Another concern is the thickness of these envelopes and that feeding may be an issue. The envelopes we've chosen are made from 0.010" thick paper, but when folded, there's sections that stack up to 4 times that thickness (0.040")... I've noticed that some of the Alps MD manuals say that .010" is the max... However, in my experience with other printers, I've been able to successfully run much thicker than the manufacturer recommends. It's also worth noting that the envelopes will be embossed prior to printing as shown in the attached image.

I wish I could say cost is not a factor, but we also don't have many thousands of $ to spend... However, if it comes down to it we could spend a couple thousand on a used printer to make this happen.

Here's my question: If you had to choose a printer for printing silver or white on envelopes, which one do you think is the best for our situation?

(Our situation: 0.010"x4 envelope material thickness, needs to print close to edge (for barcode, return address, and postage), ink needs to be durable, lower printer cost is better.)


Thanks in advance for the help!

-Scott