Is it expensive to convert a gas converted aga, back to solid fuel? can it be done?

It can be done relatively cheaply, you'll find grates for sale on ebay etc.

Few hundred quid including a corgi plumber to isolate the gas for you.

But do you really want to be continuously stoking a fire in 2009 ??

You couldn't, for example, go out for the day and then come back and cook dinner.

Yes it can be done and you will find that it is far more efficient than in its converted state. An Aga built for solid fuel has a void for the fuel which when full creates the thermal mass required for its operation. When solid fuel ones are converted this void remains empty and you never get a good constant heat