Thank you so much for being so thorough.
Have you talked to a doctor about this? I think your first step would be to find a fertility specialist and run this by her/him.
Is she normally fertile, and you are too, but you want an egg harvested from her and implanted in you? I think your first step would be to discuss this with a doctor.
This process you'll use to accomplish this is IVF, in-vitro fertilization. The costs will include --
legal fees (donor and recipient need to have a legal agreement in place,
and I think sperm donor and recipient also do)
fee to sperm donor
fees to the IVF clinic for meds administration (both women), monitoring,
egg aspiration and IVF, transfer, and other testing
medications (for her, to prompt ovulation)
medications (for you, to prepare your uterus)
probably some required tests (my husband and I had to be tested
to see if were carriers of various genetic conditions, for example)
and doubtless other things I've forgotten.
The medications are dauntingly expensive and also a big nuisance -- if you are successful as a recipient, you'll need to give yourself a daily progesterone shot in the hip muscle for 12 weeks -- the IVF clinic fees might come in at around eight thousand dollars ... probably the total cost will be between ten and fifteen thousand dollars, depending on what clinic you use. You are saving yourself at least 5 thousand dollars by having her as a donor (that is the average donor fee for eggs).
If she is donating an egg and you are carrying the baby, do you have inadequate ovaries and she has no interest in being pregnant, or is this mainly to be companionable? If you are mostly doing it for love, it's sweet, but when contemplating a baby there are better places for the money. One of you could use a donor and get pregnant, and then the other could use the same donor and get pregnant, and the children would be biological half-siblings. If you did that, you could do it mostly the natural way (my sister and her partner did it by clocking ovulation and using a turkey baster) with the only cost being for a legal agreement between them and the donor.