I don't think price has anything to do with it..... There are more places you can race a buggy - so more people are likely to end up going down the buggy route, there is more skill involved in setting them up and driving them (which will appeal to some), the level of competition is greater so it is more of a challenge to do well or to try and improve and make the next final up etc (generally, if you race a truggy these days you qualify for the A final by turning up and booking in). I used to enjoy truggy racing and have some good memories of some good races I had with other drivers where it was nip and tuck for the whole final (partly as they are easier to drive so you can concentrate on the racing rather than surviving a lap on a rough/bumpy track)....but as the level of competition fell (in terms of pure numbers as well as the overall standard)....so did the level of enjoyment....price had no bearing what so ever.
I own both a buggy and a truggy and up here at csor truggies rule the roost at the moment. Personally i prefer my buggy but struggle to find good competitive racing. Loved the Pendle NRS and Durka Durka though
My only gripe with truggies is that since they are a wee bit easier to drive and are a bit more robust they do tend to attract inexperienced drivers and crazy WOT driving lol. Wrecking both track and marshals alike Haha