For what it's worth, ETEKs and most the Planet Eclipse markers seem super reliable and well made from what I've seen. I recently got the Etha 2 and really like it. If you find a used ETHA 2 in decent condition, I'd buy that. But really, I think you cannot go wrong with any of the PE markers. The service network is also good, in case you need work on it.
For HPA, you can either get a 0.8l or 1.1l standard 4500psi bottle that shouldn't cost too much, or if you want to go less expensive, get one of the mid-size 3000psi setups.