you came to the right place. that's what this site is about, is calling sellers out on bad stuff. you're in a rough situation, but here on the forum we've seen worse. i don't think you got ripped off, but this seller and many others just dont straight talk.
many on the forum know, i say rugs like this don't really have retail value because seconds goods or low quality merchandise would not be seen in a specialized rug store with good rugs. but there are retailers who buy rugs on ebay and flip for 4, 5 even 6 fold what they pay. for the tabriz example, many of these rugs were tied up in iran during the embargo, used in iran, repaired in iran, then sent to the states when trade opened up. I once heard a rumor these rugs are not sold in traditional wholesale importer method, but on an average dollar a square foot no matter what the rug is and or condition: the importer gets what the get, a mix of okay to poor condition rugs for very cheap.
if i were in your position, i would not fret it too much or just return the rugs. These prices don't seem horrendous unless there's something seriously wrong with the rugs that i missed. the time it takes to pursue these things is not worth it, and even if you were to buy the rugs from one of these ebay dealers, you still would probably not save more than $200 for the bunch and that's sight unseen + spending a lot of time to dig through stuff you don't like and maybe even getting worse. it's what people pay to go to brick and mortar stores, maybe more or less. on the other hand, if someone sells something with incorrect information, you should be able to return without question.
If you were to negotiate, do so on the condition of the rugs, not the representation. condition is where you have leverage. the representation is just the final straw to tie your reasons together in a neat package. The seller should have some room, but you're probably not going to be able to squeeze them too much. If the rug has isolated and heavy wear, fading, loss to ends, oxidation.... these are the things for an argument.
Bottom line, these are still hand knotted rugs. sometimes you can't even get a used machine made rug for these prices. I'm not saying this to belittle your position because i know what it's like to feel gypped (even tho i don't think you were), but in the rug world, these rugs are relatively inexpensive. I would enjoy them for what they are because at some point in time, the 8x11 probably took 4 months to make.