I'm in a similar position with mine (2000 model, 128K miles), done so far this year: cam belt, rear brakes, alternator, battery, aux belt tensioner (second time in 10K miles, old alternator took out the previous one). Still need to do; Radiator, clutch, windscreen rust, possibly shocks as well. Already spent more than the car's value this year and likely to hit in excess of £4K before the year is out. However, If I bought an 08 plate 159 I'd lose more than £4K in depreciation and I'd still have to cover the servicing costs. To be fair, most 8+ year old cars with over 100K on the clock would be eating parts like cats eat tuna, I've similar nightmares with my old Saab 9000's when I was only doing 10K miles a year. So I may as well keep running this car until the gearbox lets go or it fails an MOT due to tinworm.
It does get you down, but I keep thinking, "better the devil I know". I could chop it in for a 03/04 plate car with lower miles, but chances are the previous owner will have offloaded that because big bills were imminent.
156 2.4 JTD 10v Veloce with Angel Tune (180bhp)