If you want some cheap calculators, the site BachCompany.com has quite a few TI calculators, as well as other brands such as HP and Casio. This site also offers calculator related objects and tools such as software, overhead projectors, etc.
For people looking for the CX, this is also a good place for it. I bought mine here, and I'm satisfied. There aren't any damages, and they shipped to me in about a week.
For the normal CX $124.50:http://www.bachcompany.com/product.aspx?ProductID=476
For the CX CAS $127:http://www.bachcompany.com/product.aspx?ProductID=479
For Terms and Conditions (that has shipping details):http://www.bachcompany.com/TermsAndConditions.aspx
I'm only putting this up to help, not to advertise (though it kinda is advertising...)
And for DJ_O: YES it does have Voyage 200s under $200:http://www.bachcompany.com/product.aspx?ProductID=104
The shipping and handling is a big iffy, but mine was a total of $132 from the original $127, which is still quite a bit cheaper than the base price for a CX CAS on other sites. IMPORTANT: THE SITE SAYS THAT SHIPPING/HANDLING COSTS IS 5% OF PRICE.
TIPS (for eBay/Amazon): For now, these are the more obvious tips.
1. ALWAYS look at a seller's rating. Do not risk if the seller has a low rating. If the seller has very few ratings (say, below 50 as a figure) and are mostly good, he still may not be trustworthy. The object being sold may be damaged or non-functional. There are people out there who make multiple accounts and rate themselves up. A seller who has the Top-Rated Seller badge is always a good one to go with.
2. Go through buyer reviews. See what they say and see if you like what they say
3. Check the description of the object being sold. Does the description and/or ad look promising or hastily and messily put together? Does it have a site? Does this site have a lot of buyers that are satisfied or that have at least bought from there?
4. CHECK SHIPPING. An object may be cheap, but you never know what the shipping and handling costs may be. If you can't find the cost, LOOK HARDER. Don't get fooled.
Anyone may (and PLEASE DO) add to tips or sites that sell cheaply or are very well respected.
Have fun getting awesome calcs!
edit: Thanks to TechPoweredMath.com/youtube.com/techpoweredmath for the site! He used this site to buy his very own CX CAS