The 2.0 TS is good power unit, it's revvy and sounds great which means it's also easy to drive it hard
. Things to check:
1. Timing belt/water pump/cam variator: Timing belts should be replaced every 36k or 3 years whichever is sooner. The 2.0 has a cam variator and when this begins to wear it can make the car sound like a clattery diesel, as the timing belt has to come off to change the variator it's a good opportunity while you're there. Plus have a good look at the history because the cost of a thorough service including a timing belt + tensioner + idler + balancing gubbins, water pump, variator and 8 spark plugs will be... sizeable.
2. Oil: TS engines are designed to use some oil and this should really be checked weekly, if it's low then I'd be walking away.
3. Body: Floor pans can be an issue as Alfa didn't bother to properly underseal all of them, don't be afraid to have a good poke around. Body panels are quite thin and damage easily so check for panel gaps and accident damage.
4. Selespeed: There is a Selespeed expert on the forum somewhere so have a quick look at some related threads. A lot of people report minor niggles with the Selespeed system but a bad one will take every opportunity to raid all the parts in the shop so have it properly checked over, Selespeed parts are pretty rich now.
5. Suspension: Suspension consists of double front wishbones and trailing arms at the back, the front uppers are known to squeak when the bushes wear and should cost around £90 a side all in. Lower wishbones tend to last longer but the subframe has to be dropped to replace these which is probably 4 hours labour plus £80 per arm. It's a good idea to polybush the anti-roll bar during this repair for just an extra £30. I've never had the rear arms replaced but I know that there are three on each side and the parts alone might cost £130-£150 per side (assuming worst case), check the link below and you'll see what I mean. Plus, if you do need to replace suspension bits then replace them with original TRW parts, they are just better. Rear hub bushes are known to wear and require fairly regular replacement but these are just a few quid each. It's a good idea to get an alignment after any suspension work to be on the safe side.
6. Odds & ends: A sloppy gear lever could be indicative of worn top-hat bushes, again just a few quid and maybe an hours labour. Exhaust backboxes are prone to corrosion but if it isn't blowing it's really just a cosmetic issue. Handbrake cables/brake flexis on older cars might be starting to wear, flexis on all four corners + handbrake cables will quickly add up.
There will be bits I've missed but this is a good start and the people on this forum are a helpful bunch so do ask around, I've learned a great deal about my car just listening to the forum. I'm not trying to scare you away it's just that the Selespeeds are notoriously complex and getting on a bit now. As you mentioned you'd rather not spend a load extra fixing the car up, that said, buy a good one and you'll enjoy it. Best of luck with the search.
Alfa Romeo 147 Buyer's Guide
147 Sport Q2: Autolusso Remap + Swirl Flap & EGR Delete, Mocal Oil Cooler Kit, JTD Performance FMIC Kit + High Flow Elbow, Wizard Downpipe, PF Pads + 5.1 Fluid, Autolusso Braided Brake Lines, MTech Short-Shifter, Autolusso Silicone Turbo-to-MAF Hose, Refurbed Q2's + Some to add later.