That's because your valuation of your material is way too high.
You may have paid that much new, but here it won't be worth anything near $700.
The printouts and note cards are worth what someone will pay, but you likely won't be able to sell those.
I purchased a like new set of TBR, EK 101, EK 1001, and TPRH verbal for around $200.
If you really want to sell your items you should update your thread with an itemized listing and drop the price tremendously. If you think they are worth that much you can keep them where they are, but it's a free market and I don't think your items are worth more than $300 for everything.