O-200 connecting rod part number 530184A2 has been replaced by 654795A1, only $1,214.88 new, through one of several Cessna dealers (out of stock). Airpower shows it (call for availabiity) for $1,079.90. I googled both part numbers and prices used run from $110 for one on Ebay to over $250 from various salvage yards.
There's nothing wrong with using used rods (every engine flying has "used" rods installed). However, I'd send it to a reputable machine shop/engine rebuilder to be checked for trueness and cracks, and it probably should be re-bushed. The weight is going to be off by several grams either way... not very important unless blueprinting the engine.
Otherwise, remove all four rods and have them weight matched and balanced.
http://www.ebay.com/itm/Continental...sh=item1e9bb25592&vxp=mtr#ht_2325wt_1106http://www.airpowerinc.com/productcart/pc/prodparts.asp?catid=1&subcat=108&mfgid=TC&prodid=29540