Some of the cheaper units are more for run of the mill installers some of the more expensive jobs have more strict apps. and maintenance schedules ie; cooling a house vs cooling a mechanical room.Some contractors think that(or try to make you) $$$$ equals quality as you can see by the pix. this looks like a unit with a pretty specific application and a much broader preventative maintenance routine.
Im sure you just want something that you just have to change the filter once in a while an then have some kinnda warranty
Ive has good luck with Goodman. I hear they come with Copland Scroll compressors, which Rheem uses. And offer a 10 year warranty. Plus you cant beat the price. I can get complete systems for about 1500 bucks