Edit:
All buy walls on all exchanges are mostly fake. BTC isn´t worth more than 200 bucks.
I'll bite: I even offer you a 50% markup to the price you state. Please let me know how many Bitcoins I can buy from you for 300 bucks each.
Of course you can manipulate the market. You put up a huge fake wall [...]
Problem with that is, that we have regular price fluctuations and BitStamp order integration. Your fake, inflated offer would be taken pretty quick, by someone wh didn't even look into the orderbook. Your fake wall doesn't show up in the BitStamp orderbook to begin with..
Maybe you could manipulate the BitFinex book a bit, but not to any amount that it's far away from the BitStamp rate.
And, in general: I stopped bothering being clever with the orderbook. The market moves quicker than my strategies work out, so I make better trades when more-or-less dropping it all to the orderbook.
Ente