Well, in order to buy, someone needs to sell, right?
I will start with some of mine initial coins, then the strategy is:

• Person X buys coins on gridcoins.org
• I sell them from my wallet
• I use that money to buy more GRC on exchangers to buy more GRC.

Result: Increased trades on exchangers, increased number of Fiat->GRC = deflation.

The cost is going to be a bit higher then the GRC value due to conversion costs, but definitely lower then 'VirWox' approach, as I am not going to generate profit.

In the later stages, other crypto -> grc will be also enabled, allowing to completely close the circle and allow trading in both directions.

The reasons why not doing it now, is not having enough fiat / crypto cash flow, and the demand for selling is probably more then for buying, which will directly cause an inflation. (not only with GRC but with any crypto allowed to convert to fiat directly assuming there are more crypto-> fiat then opposite direction).

In short, conversion in both direction is going to be allowed in later stages, but it would never be allowed that grc->fiat, exceeds fiat->grc.

We will need to play a bit dirty here :) But in principle, the is very similar to steem economy.