I recommend trolling ebay. Find a set of nice used Works Performance or something like that - used of course. Take a careful look and read the description closely too. $100 has scored me good sets of shocks before, just don't get caught up in a bidding war - unless you are bidding something I am selling
My favorite shock secret is to find a pair of use Fox snowmobile or ATV front shocks in the length you want then revalve them to your liking. These are really cheap to buy since they are plentiful. They are really nice shocks too with durable steel bodies, DeCarbon style too so the oil and air do not mix together, and they have really high quality pistons and normal valving stacks. They come valved awfully stiff though so the revalve and normal vintage shock springs are a must. $50 for a very nice pair, give another pile of coin to the rebuild guy and maybe reuse your original shock springs. Anyway, good shocks for cheap do require a bit of creativity. There was a good guy up in Canada not long ago who sold shock valving shims and even offered a ball-park assortment of shims and suggested valving that was pretty good. I don't remember how to reach him, but I found him through basic internet searches. If you get to where you can revalve the shocks, then you can have nice vintage shocks for little more than $50.