Dollar cost averaging approach to Bitcoin investing? Are there any services offering a dollar cost averaging approach to Bitcoin investing, i.e. something like an index tracker fund which purchases a set amount on a regular basis? If not, are there any reasons why such a service can't exist:


Are there any theoretical disadvantages, i.e. anything specific about the asset which discourages this style of investing?
Are there technical limitations, e.g. is there some restriction imposed by payment bodies which would prevent making a regular payment from Paypal to Dwolla, from Dwolla to an exchange, then buying coins, in an automated fashion?
This can be done today.

Dwolla lets you send money to Mt. Gox on a schedule:
 - http://help.dwolla.com/customer/portal/articles/164379-multi-payments-schedule

You then can leave an open market order to buy bitcoins, e.g., a bid for 10,000 BTC.

The moment new funds arrive from Dwolla, Mt. Gox will attempt to execute the remaining part of the order using all USD funds available in the account and those bitcoins will be purchased at the market price at the time.

Of course, this assumed the account is not used for any other trading, as that open bid order would be triggered from any BTC sales that occur.