Rabbits are delicate. Even the hardiest bun is like a critter made of blown glass; I'd refuse to allow some strange rabbit anywhere near mine. The exception is at a show...where I run the risk of killing my whole herd every single time I attend one. :/ It's a risk I feel I must take...but it isn't one I take lightly.
Your doe could be infected with any number of problems by an outside buck. Remember, stress drops the immune system and rabbits stress out whenever they go anywhere, so taking your doe to be bred could cause her to be less capable of fighting pathogens. Plus the stress means she likely won't conceive well. You could end up killing her or nearly so, and NOT even get a litter out of the deal. When a good buck probably won't cost THAT MUCH to acquire and quarantine, why not buy a buck?
Owning your own buck is one of the best ways to go IMO. I bought a buck for my special favorite doe...took me a long time to get her pregnant due to some conception issues (she kept reabsorbing the litters or having stillborns) and it finally worked out! If I had to pay to have a stud "service" her, I'd have had to lug her over there dozens of times.
Plus, many people breed a doe two or three times. Does are "induced ovulators" so the first mating usually causes the eggs to be released...then between 5 and 10 hours later, most breeders re-breed the doe, to fertilize the eggs. My doe with conception issues, I had to have her in with the buck every hour ON THE HOUR for almost a 24 hour period before she gave me her first litter; this last time, I bred her on four occasions within a 24 hour period, with at least three successful mountings from the buck. No way do I want to haul her over to a buck's place four times!!!!
Plus, your doe may be carrying some pathogen to which the buck at stud has no defense against (many isolated herds have great immunity against their own "bugs" but totally lack defenses when it comes to outside strains!) and even though it won't harm HER, that buck could be infected and die...and possibly kill the buck's owner's whole herd as well, if they don't quarantine.
There are so many reasons not to allow contact with an outside rabbit. Consider buying a very nice buck of your own.