I've recommended the JVC TMH-150CGU 15-Inch color production monitor numerous times and no one who has bought one been disappointed with it.
It's a 750 line display (translated: hi-res) monitor with underscan, blue gun only, monochrome switch, 43:/16:9 switchable, etc.
The B&H price is $470.00
edit: you can use an A/D card like the ADVC-55 or a miniDV camcorder that has pass-through to convert the signal from Vegas (firewire) to the monitor (analog aka composite video).
The camcorder can be non-functioning from a tape transport POV as all you need is the electronics to be working.
I will heartily agree, the JVC is a most capable tool. Takes no time at all to calibrate and best of all, you can trust the results. I use an ADVC-300 to feed it and couldn't be happier.