This price has been slightly increased, now $220 per unit because six units have already been sold.
I am selling existing mining rigs, $220 per 250mhash/sec. They are online now, and you get daily dividends. I operate them for you for $1.50/day in upkeep until it becomes unprofitable or you want to stop. Then I either send you the computer or sell it for you and give you the money. If something breaks while you pay upkeep I replace it for you at my expense. If there is downtime I cover it for you. You can buy individual units, so you can own just one unit for $220, but in order to redeem for a full rig you would need at least two shares and to pay for shipping from the east coast of the USA.
I will also be willing to lease the equipment to you if you do not want to be bothered with owning it at the end. The lease rate depends on the terms, with more favorable rates for longer term leases. With leases there is no upkeep cost and you receive no variance payments daily. A one month lease is $120, two months is $220, three is $300, and additional months are $60/month all paid in advance. That's as low as $0.24 per mhash per month. Compare that with the prevailing rates. If you rented 1 ghash from me for 4 months it would cost you a total of $1440 ($360 x 4), while others would charge 1760GBP, which is more than double.
In either case the payments are all zero variance, so downtime is never an issue. Payments will be based on the rate determined here
http://www.alloscomp.com/bitcoin/calculator.php, which at the current difficulty level is .182btc/day per unit purchased or leased. If you own and I operate, the upkeep costs are taken out of the daily payments at exchange rate at the time of the transfer.
I would prefer payment via some method with no chargebacks, so I will gladly accept bitcoin or Mt. Gox transfers when they reopen. If you have any questions please post or PM.
This isn't super relevant to the mining operation, but if you are worried about security, I also have an ebay business with nearly 10,000 feedback and monthly sales of around $30,000. You will have all my details to see that I am legit.