I say buy a place if you can, it is worth it in the long run. Interest rates on home mortgages are low right now. You can get an $8000 first-time homebuyer tax credit if you buy a home before November. The housing market is down, so property values are the lowest they have been in recent memory. Also, the housing market is expected to rebound eventually (but when this will actually happen is anyone's guess), so if you do buy, your home should appreciate while you live in it assuming you do your part and keep it nice. Lastly, there are many great deals on houses in the current environment due to things like foreclosures, short sales, and people trying to downsize. You might be able to find a house that is priced well under its appraised value. These are all good things.
HOWEVER, buying a house/condo is probably only feasible if:
1) You live in a smaller city/town where property values are lower
AND
2) You have little to no undergraduate debt
AND
3) You are in a fully funded MD/PhD program and get a living stipend
AND
4) You have significant money saved from working prior to MD/PhD
OR
5) You have a spouse that currently works and makes a decent salary
OR
6) You have financial backing from your parents
Buying and maintaining a house is more complicated and expensive than many students realize. First, you have to qualify for a large enough mortgage and cough up enough cash to make a down payment. Whether or not you qualify for a mortgage is based on your current income, and a living stipend from an MD/PhD program won't get you very far in that regard (hence #4,5,6 above). But even if you do manage to get a mortgage and purchase the house, the monthly mortgage payment is only one component. You have to pay closing costs and fees to the title agency. You have to furnish the place. There are also property taxes. Home insurance or condo fees. Utilities. Maintenance costs, for things like appliances and general upkeep. This stuff adds up fast and starts coming non-stop the day you move into the house. Your roof could get demolished by a huge storm the day after you move in, and you'd have to fix it ($$$), or your toilet could develop a small leak and water could start seeping into the flooring and basement ($$$), etc. You get the point.
Basically, if you want to buy a place, you better do your homework and carefully consider your income and potential expenses. I would strongly encourage renting rooms of your house or condo to other med/grad students, but this may not be practical if you have a spouse or family. If you find a good deal on a property and rent some rooms to other students, you can live essentially for free while you are in school, and you'll be building equity in your home with each mortgage payment. Once you graduate and move on to the next phase of your training, you can either rent the property or sell it and end up with a nice wad of cash. It definitely beats throwing money away on rent every month for 8 years.
