I have the Dowelmax, and I think it is a great tool. Easy to use, and dead accurate as long as your wood is cut square. I have used it to attach aprons to legs on a small hall table, and (instead of biscuits) for larger panel glue-ups, frames,etc. Pricey, but worth it in my opinion.
I have one something like Don's. Unless you're going to do an awful lot of doweling or have some special needs, I think it's all you need. I think I paid maybe $40 for mine (but I don't really remember). I don't do a lot of dowel work.