[MartinP]

Standard resin-coated paper in a large enough size would already be a decent material for hand-made album sleeves wouldn't it? A couple of mockups (prints held together with tape on the back, plus the tabs for gluing), opened out to look like the 'flat' that you'd get from the usual commercial offset-printer, then photographed on the largest neg you can manage. Print the flats on 20x24 or 16x20, trim and glue, slide into an acetate sleeve and there you go??

Edit: You could even use a heavy (300g/sm) FB paper as something like ART300 would cost you a bit more than ten GBP, $16.60, 12,70 EUR per sheet, plus your time and construction materials. It would easily add a lot to the cost (and value?) of the product.