Uhh... why not just use the BitShares DEX? That's its purpose.I am not 270-290 BTS/bitUSD desperate... That are the regular sell orders as of this writing...
Edit: I just realized the market engine has a matching bug (again ). However, from what I understood, regular BitUSD sell orders (not shorts) would still match with your buy order.
You don't buy those sell orders. You put a buy order at 225 BTS/BitUSD and wait. If no real BitUSD sell order matches at that price, then you probably won't be getting anyone PMing you offers either.
Also, if I understand the margin-call mechanics appropriately (and they are working according to theory other than the current short matching bug), then there is a (currently invisible) buy order at 10% above the feed price (so around 245.9 BTS/BitUSD). And that should be a buy order for at least 80,000 BitUSD. So if I am correct about this, then unless you are willing to increase your price to 246 BTS/BitUSD, you probably won't get a match anytime soon.