Buying is a good idea, its not like scaffold eats so they are cheap to keep around. Besides, its not like they will be at your house very often anyway. Aluminium planks are very nice and worth the money to me but Im not 18 anymore so the heavy wood planks are tough on me. A 20 foot pick is nice to have around too but ya have to be careful not to walk off the edge of them.
My rings were bought over time and are different brands. Thats usually a problem from the different pin spacing. I just added new pins in the proper spacing so all my rings match now. Well worth the time to weld them on and they were cheap. http://www.ebay.com/itm/10-New-Quality-Scaffolding-Drop-Lock-Replacement-Rivets-for-Scaffold-Frames-/290616159370?pt=LH_DefaultDomain_0&hash=item43aa12ac8a#ht_2616wt_1030
Just watch our for the usual signs of beat up rings and you will be fine.