It's hard to say from what you have posted as a description. I've been mucking about with one of these for twelve years now. I love the car, but it is a constant challenge. I have had years of limited repair and maintenance costs for the car, and years where all hell has broken loose.
If there is rust, that is usually the determiner as to whether there is any chance to really rebuild a 108. Rust is BRUTAL to this chassis. The usual places to check are the eyebrows above the headlights, behind the front wheel rockers, behind the rear wheel wells and all four wells themselves, and the trunk floor. It's also important to check around rear suspension and axle mounting points. Be sure to check hard! The undercoating on the car's rockers only worked to hold the rust in place and it can be a deciever. Also be sure to pull the plastic wheel well liners out of the wheel wells to see what's behind them. Dirt usually gets trapped there and promotes rust by the load.
Mechanically, the car is complicated for its age and has lots of parts. At this age, all of the rubber should be checked to see if it has been replaced or not and for condition. For instance, the engine mounts, flex disc on the drive shaft, injector hoses and fuel lines both into the engine bay, behind the front driver's side wheel and at the rear from the tank to the rail have to be checked. Those are just the beginning. If maintenance has been done there, and there isn't too much rust you might have an OK car. I love mine! It's a blast to drive, and it's one of my favorite mercs for styling, but they sold well, and they can be found fairly readily today. Coupled with the high repair costs this makes for a limited market and a limited resale price, even in good condition. Check E-bay for them. There are always a certain number going and relatively rust free good condition units do not fetch a high premium.
My advice would be this: If you have an example which evidences good general maintenance, runs well without heating up, and has limited or acceptable levels of rust, then it's a good car to keep as a labor of love. It will pay in driving joy, but economically it is not a winner. I do alot of my own work, and I have been able to keep my car on the road for all but two of the twelve years that I have owned it. It has somewhere around 150K miles on it (odometer was broken for a while which is also a common problem), and last year I had to pay a pro to pull the entire rear end and drive shaft to reseal all of the seals in the rear axle, replaced a universal joint in the rear axle that was rattling around loose, had the rear universal joint replaced in the drive shaft (technically the whole rear half of the drive shaft is just supposed to be replaced since it is a pressed in unit, but I had it rebuilt at my risk to save money) replaced the center support bearing, rear mount bushing which was completely obliterated and second flex disc in twelve years. I also replaced a number of other things myself last year such as the transmission linkage from the column shifter and a couple of other things that went bad. This was a little heavy, but not an atypical year with the car. If you want to make money then you are really beating against the wind. If you want something fun to toy with and drive in the summer, it's a great car . . . without killer rust.
As for the wood, that's pretty easy to fix yourself, and if you search the net, you can find a pretty good site that will walk you through the bulk of it.
All the best -
H