Well, I guess I'd have to politely disagree that only a 'pro' can do this, as I'm going to tackle my top on my 560SL in a month or so. Granted, it is a job for someone with the skill set required, so if you can do upholstery installation, or similar work, armed with the right instructions, I believe it can be done by a non-pro. I know there are several here that have done so (and a few that wouldn't go there again).
Here's a link to one instructional bit that might give you an idea of what's involved
http://www.vcnet.com/worlduph/mbtopinstall.htm There are very few good documentaries out there, at least that I could find. What I did was buy a copy of the Robbins video off EBay. The same is available for a price from Robbins too.
As to what top to buy, I started a thread on this but received few responses. Maybe I should bump it now that the nice weather is finally here and others are looking at replacement.....