There's so much good stuff out there in the way of used Part90 Commercial gear.... I've got a couple PM400's, an XPR5550 (shop truck), an old TK-880, and an assortment of portables that run the range from Vertex through Motorola. I've always been a fan of the M1225 for starter gear. It's small enough, has decent specs, and the software is very easy to use. I've picked up units off eBay for under 25 bucks for low power (25 watt) 4 channel models. The 20 channel display units usually run higher, but almost always under $100 for clean working units. The M1225 series was also type accepted for Part 95, which calms some people's fears. I have to admit that having access to all the software and cables makes things pretty easy for me, but unless you're looking at current model top of the line stuff, the software is pretty easy to come by, and most of the mobile cables you can make yourself if you can follow a diagram on Batlabs or Repeater-builder.