Legal Question in Wills and Trusts in California

If trustee is the only beneficiary he doesn't need to buy the house. If there are other beneficiaries, he'd better make sure they all agree om writing with the price and other terms (because of duty of fairness and loyalty, and to avoid self-dealing.) Not sure what closing costs you are referring to, but if there is a lender involved, there will be the usual title company/escrow costs.

I agree completely with Michele. Trustees are generally prohibited from engaging in transactions with the trust on their own behalf, unless they are the sole beneficiary, in which case as long as the terms of the trust don't prohibit it, you can just transfer the property to yourself without buying it. If there are any other beneficiaries, the closing costs are the least of your worries. You need to consult with an attorney about how to conduct this transaction or even if you can. They will include allocation of closing costs in that advice.