Take a look at sysracks. They have a story of different racks all at different price points. Additionally the way they provide the rack, you can choose whether you want the doors on or off. In my case I put the doors on because it's in a closet with a separate AC Unit

In terms of starter rackmount this is a great one. I started with an R710 a few years ago as I needed more processing power than a traditional tower offers. Few years after that I got an R720 for work in my colo.

Two great servers!!!

You need a 19u (basically a quarter cab) with 35" depth. That will allow you to get dell ready rails and easy mount