If there is male factor infertility, it can commonly be corrected with using ICSI or TESE as a component to IVF. Have you looked into either procedure? ICSI is probably much cheaper and less invasive than TESE and there would be no need for a donor if you used either. As long as there is a little bit of sperm, ICSI can be used. For instance, if 30 eggs are extracted from your wife, the embryologist only needs 30 sperm. If there is zero sperm, then TESE might be an option if doctors determine you're a good candidate.
Also, success rates will vary greatly depending on the patients. The younger your wife is, the better your chances. Even if she's older, there's still plenty of hope, especially if you have excess embryos to freeze (because that's more opportunity for future attempts). I had my child in my late 30s after an IVF/ICSI cycle in the USA.
I don't know if this will help, but if you visit this web site and under the "diagnosis" box, scroll down to "male factor" and then click "Apply filter." It might give you an idea of what success rates are like on a broad level. It's categorized by age of the woman (>35, 35-37, 38-40, 41-42):
https://www.sartcorsonline.com/rptCSR_P ... inicPKID=0
I don't know if Singapore requires fertility clinics to release success rates. It's probably best to contact individual hospitals/doctors for questions. I would think that legal issues would be worked out between the donor and hospital ahead of time (with the donor filling out paperwork) but I can't say for sure.
Best of luck to you both on your journey to parenthood!