My vet wants to charge me the cost of a visit plus what it will cost to do the test. All together that would put me $100+ I think I will be fine not knowing for that price.
Your conure should be seeing the vet, anyway, for a new-bird physical and yearly check-ups. Adding the cost of sexing to the first of these visits doesn't make much of a difference. I can understand if you were just "given" this bird that you might not have funds available right now for a vet visit, but it is really part of the cost of having a pet parrot. After the first one, if you simply put a a few dollars a week every week into a jar, you'll be saving enough for yearly check-ups.