You can buy tradestation2000i but not 7 or 8 as those are internet/server based which connect to their "on-demand" datafeed. With TS2000i, you need to collect your own data. More problematic.
Which are the 'current' datafeeds that the 2000i is able to manage thanks to the globalserver (or with alternative add-ons)?
If you plan to use TS2000i for backtests make sure you umderstand its limitations http://www.elitetrader.com/vb/showthread.php?s=&threadid=158397&perpage=6&pagenumber=12
I found Metaserver for DDE, IB, MarketCast,QuoteSpeed, QCharts, IQFeed, Realtick III... ... anything else for Zenfire or TT Fix datafeeds?