"so a 19"-21" size is required. It must have built-in speakers and a DVI or HDMI connector."
Can anyone recommend something here?
Since you're looking for something that size then there are many 24" LED backlit models in the $150 range. I think an LCD TV in that size would be more dollars. Getting a monitor with speakers may be a bit harder though. Also, speakers on a monitor are typically powered by the PC so wouldn't work with the sat receiver anyway, forcing you to get powered speakers anyway. So maybe you are back to the LCD TV if you want built in speakers.
Panny TC-P60GT50, Bell 9242, Yamaha RX-V730, Paradigm Cinema 70, Harmony One, HTPC