Patience is your friend. If you are desperate to get something quick you may not get the best deal unless you really luck out. Lots of people give up on machines that won't start when many times just a good carb cleaning they need. Look for ads that say things like, "It ran last time it was parked, wont start now, best offer". Fair chance a carburetor rebuild/cleaning is all it needs so that's a cheap fix, especially if you can verify it has spark. You probably don't have the evil ethanol in your fuel over there so carb problems may not be as prevalent as they are here.
Once you find an old gem for cheap that you can fix up and make good use of you will be hooked and you will start looking for other things you can fix up to use or sell. Lots of folks make a few extra bucks doing that on the side around here. I've flipped a couple old machines for profit myself and it's very rewarding. Can't say it's always worth the time put in but it's a fun hobby so I don't worry if I end up making only $5 an hour on it. As long as I clear the expenses and save a good machine otherwise destined for the scrap heap I'm happy. Old machines (pre-1980) are always built better than the throw away junk they sell now anyway.
I have a 1976 Troy Bilt Horse rototiller and a 1960-something Gravely walk behind brush mower, both of which were fixer-uppers that have paid for themselves with the side jobs I got tilling and clearing brush. So now I have those machines for free and if/when I sell them they will be pure profit and would be worth about $500 each. Unfortunately my house is a fixer-upper too so I don't have time to do as much mechanic work as I'd like.
Best of luck, don't forget to keep us posted when you find something (pics are always appreciated).
