As above - I'm finally taking the plunge and having an arena put in at home. The best quote so far is from Grand Prix Arenas - has anyone used this company? Feedback good or bad please I would hate to get this wrong!
Read the small print. I found some of the more well known companies had odd terms like it being your responsibility to tow out any lorries that get stuck or not their responsibility to tidy up and dispose of waste/excess soil. Also make sure that they have a good customer service if things go wrong. My whole membrane shredded within 3 months mixing sand and stone. The whole base had to be dug out and surface completely replaced which the company did no questions asked. This is easier if you use one single company to build and supply the surface.
Sorry I can't help about Grand Prix but I'd advise going to see a few of their arenas in use.
