I chose a donor through a clinic, but I went out of town. I went to Oregon Reproductive Medicine in Portland, OR. The recipient has the option of meeting the donor or doing a semi-private donation, depending on what the donor is willing to do. We had email contact with our donor, facilitated by the clinic. Our contract stipulated that we would pay for her to sign up with the Donor Sibling Registry, and the donor agreed she would be willing to sign up with them. It's not a guarantee that the child will be able to contact her later, but it's better than nothing. Donors at ORM are also able to choose to be completely anonymous.
I think San Diego Fertility Clinic (?) may allow similar arrangements.
Thank you, OP, for being willing to do this. It means the world to parents like me. If you want to look into donating through one of these out of town clinics, you should contact them. The recipient couple would be the party responsible for your travel expenses. I got the sense that ORM took good care of their donors. Our donor had donated previously, and before I got kicked out of ORM's donor database due to pregnancy success, I saw that "our donor" was back in their system. She must have had a good experience going through the donation that resulted in our child if she was willing to do it again.