I managed to get genuine colour coded floor mats with perfect fit, very cheeply for my W116. It took nearly two years of patience. I went to Pick 'n Payless (junkyard) and found the grottiest mats available: covered in grease and dirt. The front two mats came from a 450 SE and a 280 SE. The rear mats needed to come from an SEL, hence the patience. Actually, they came from a 450 SEL. They were also saturated in oil and dirt, not a pretty sight.
I ripped the sponge backing of all of these mats, and drowned them in alkasteam, and set to work with a seriously industrial water blaster. It took about 20 minutes to scour each mat clean, and would you believe, the carpet top surfaces came up like new. They now sit in my car as if they were the original mats, only they are not. They now serve as protective floor mats, even though they started life as original carpet mats, with sponge backing.
Total cost? about $20, patience, and some simple work.
I happen to work for a new car dealer and I occasionally come across new floor mats still in their packaging, which for various reasons, are to be disposed of. I keep an eye out for this sort of stuff; I can take it if I want, but I am not allowed to sell it, but I am free to give away to my friends. This applies to all sorts of items: used micro fibre cloths which can be cleaned, chamoises, car detailing samples and vehicle accessories, which would otherwise be thrown out. I have completely kitted out my Skyline and Camry with bonnet protectors mud flaps headlight protectors left and right weathershields, wheel covers, sheepskin seat covers and floor mats. Over the years, I have not sold any of this sort of material for a cent, but I have given quite a lot of this type of clobber away. Mostly, I have been asked by my employer if I want it; occasionally I have asked if it is available. Ethically, I would be going into competition with my employer if I did sell it.