Richard, if you buy off eBay, make sure it is the 200volt class, as that will run on 240VAC input, the 400volt class which are common, require the 440VAC input power. Also, they typically do not come with the manual, so take the part number and brand, and find the manual online. If you can't, don't look further. There are brands like Rockwell Automation (Allen Bradley) that I've found don't keep old pdf's of their products available.
For brand new, I have purchased from:
They have typically had the lowest prices I've found on the web. You DO want a VFD that has sensorless vector, in its design, as this allows large torque at low operating speeds (I can drive a tap or die without backgear and very low speed on my belt driven lathe left in the middle speed setting). You do not need to oversize a VFD that accepts single phase input, unless exceeding 3HP. Down load the manual and see what the installation requires. Just in case you don't know, NEVER switch the output of the drive between the VFD and motor, this must be hard wired. This is what will damage the output transistors in a VFD. Also for connections less then 10 feet between the motor and VFD, you do not need any filters. And really this only starts being a problem in large HP motors.