I haven't bought one in a while, but I was getting the T410 from the Dell outlet for a good price. They're relatively large Tower servers, but they support 6 drives, either hot swap or fixed config and are basically silent. You can also add a 3 bay ICY-DOCK type enclosure into the 2 5.25" bays to get a total of 9 drives in the system if you need that many. I have 5 in office environments and they stay cool and run with 9 drives just fine. I use the LSI 9211-8i cards inside for drive connections.
The T420 is the next generation and is still shipping new. It also looks like the T110 supports 4 drives and is/was on sale with a coupon for around $250. I would have to confirm, but it looks like with the 5.25" dock you could probably get 7 drives in there..
Just be aware that Dell has different chassis under the same model number and not all support the full compliment of drives. You can select the chassis you want if you buy new, but when you use the outlet, you have to look at the configuration details to verify the chassis type.