The Sig LT40 ARF is very good trainer. It will fly well with an OS .46LA. If you build it yourself and buy a good 4 channel FM radio you can get by without going much over $300/$350. Don't overlook the cost of field equipment such as fuel, glow igniter, props, chicken stick or starter and other miscellaneous little items. Some of the best advice above is to visit your local field and ask questions. Other costs factor in on the BIY route. Glue, both epoxy and CYA, covering material, covering iron etc.. As to buying off Ebay look at the disclaimer at the bottom of each page. Ebay has not checked or confirmed any of the material listed. Caveat emptor. Check RCAirport or RCUniverse which will soon? be one. Buy from other modelers not a bunch of people who say "I'm not a modeler so I don't know anything about this but it was purchased at a yard sale, or It was part of Grandpa's estate". A lot of the people are also dealers who have bought up a bunch of surplus stuff and are trying to sell it for more than it's worth. Stick with the people you can mostly trust. Some of your local pilots may have something you can buy for a reasonable price and you can ask to hear it run and see it fly.