Beewerks,
Do plenty of homework and research from local and regional advertising sources, such as Craigslist. This would give you a baseline of what TW's are selling for in your area.
I did some searching on Craigslist in the western U.S., so here are a few examples for pricing comparison. Should mention, there are not a lot of TW's for sale on Craigslist, so search other options selling motorcycles.
1) 2001; 1,100 miles; $3,000; Idaho
2) 2006; 3,800 miles; $2,900; Idaho
3) 2002; 4,995 miles; $2,450; Salt Lake City
4) 2005; 319 miles; $2,500; Las Vegas
5) 1987; miles nl; $1,200; Fresno
6) 2002; 2,200; $2,200; Denver
I'm sure better deals can be had. What you want to pay is your personal choice of what your willing to pay.
For many reasons, O-Ring chains are the best way to go, but I didn't look up a price.
However, to just give you an approximate cost on OEM chains and sprockets, though the range can vary, these would be around $30-35 for each. Again they vary quite a bit, so searching around local dealers as well as the on-line M/C dealers is the way to go to get the most accurate pricing.
Good luck on your search.