I haven't found it to stain my fermeters if you use it at the right concentration.
I really rate this stuff, it is super good. I can't taste any residue either and I've never had an infection with it. It's my favourite sanitiser.
It does turn silicone hose pink for a while but it goes back to white. I think sunlight would probably make your fermenters white again Pumpy.
To save on iodophor usage I only use 1-2L of sanitiser to sanitise my fermenter on brew day. If your fermenter is clean then it shouldn't be hard to sanitise. I put 1-2L of water plus 1-2mls of iodophor then routinely shake the hell out of my fermenter every 5 mins or so to splash the solution around. This has been my standard procedure for the last probably 10-15 brews and it's never caused me any trouble with infection. It makes the iodophor solution go a long, long way.
If you want to do a bulk buy of the solution you can buy it in a 25L cube for about $125 (=$5/L) and is sold under the name of Alfa Laval Agri LF12 Milking Machine Sanitiser. The Active constituents are: 12gm/L available Iodine, 252 gm/lL phosphoric acid. It's a low foaming acid dairy sanitiser. Probably more easily accessed in a rural setting but you should be able to find a distributor in the city somewhere.
Cheers, Justin
Edit: Added more Alfa Laval info.