The Vortex SPARC and Strikefire seem to get good reviews even after hard use. You can usually find them on ebay for around $200. They aren't built or designed as well as an Aimpoint but they do have a lifetime warranty and you can buy 3 of them for the price of an Aimpoint T1 or H1. The Vortex RDS's use some goofy battery sizes but they are available.
If its just going to be a range toy then the Bushnell TRS gets ok reviews. I doubt that it will hold up to the type of abuse the Vortex optics can but again they sell for around $100. Mission drives the gear.