Pedals first, TrackIR second.
Pedals is a must for serious flying, TrackIR is luxury.
Pedals is functionality. TrackIR is immersion.
I have had a stick with a twisting-grip long time ago. It does not compare and cannot replace pedals. Both are worlds apart.
But I agree with people saying they would not fly without TrackIR anymore. In the virtual cockpits of FS9 it makes all the difference and turned the sim into a new world indeed.
Get both, therefore. First the pedals, later TrackIR.
Regarding pedals, the best I ever saw and tried in the price segment below 200 bucks, are Simpeds. They are more comfortable in foot spacing, and are a robust construction, working very precise (with adjustable movement-reaction-ratios). I use them myself. If needing to buy new ones, I would buy the same again. Some spare parts also can be ordered separately. I never heared of anyone needing to do so though. My set works flawless since over nine years now.
http://www.dhs-electronic.de/index2.php?lng=en
And btw, TrackIR is at version 5 already.