I guess the hard thing would be is knowing when a horse is actually going to start under $2. You'd need something checking TAB odds right to the jump and then backing on betfair. Probably can be done, would be an interesting system to try out.

I do know from my laying adventures that the short priced horses are hard work to eek out a profit from laying. From my thousands of lay results, I have found that those horses starting short in the market, generally $2.50 and under are in profit at lay prices, so perhaps a slight profit/break even at back prices (as lay prices are generally a little higher than available back price). From this I wouldnt be surprised in teh least if backing all the short priced favs would return a POT, albeit most likely tiny.