Hi Vanessa,
Sounds like an absolute minefield to me, and I'm afraid like everyone else I'd suggest that you don't go any further with this little pup.
Puppy farming is an absolutely awful trade and unfortunately the only way to stop it is if the demand for farmed pups is stopped, and that means that pups like Megan should not be bought, however hard it is to turn your back it's for the best.
A puppy bred from a reputable breeder should be the bench mark for every potential puppy buyer as it helps ensure that the welfare of the individual pup, it's parents and the breed as a whole is upheld. Also as a buyer you will be given a lifetimes worth of support from the breeder, which is invaluable for a first time dog owner, and still very useful and important for experienced dog owners.
From a repuatbly bred pup you will also be able to trace back it's ancestry and have a better idea of any inherited conditions or behavioural problems (which should have been minimised through health tests).
If the gentleman that has Megan at the moment is very ill and has been for a while, then I very much doubt Megan will have come from a reputable breeder in the first place, as the man would have been considered as not being able to offer a good home. Also like others have said a reputable breeder would have taken the pup back or helped in finding a new good home for the pup without question.
Give your local dog warden a call and explain the situation with Megan and they may investigate, so try and help Megan in that way, but do not buy her
Stick with the reputable breeder you know and get a pup from their litter, as you will be garanteeing your boys a healthy, confident, well socialised little pup with all the friendly back up you could possible want. Maybe disscuss Megan's situation with the reputable breeder, so that they may be able to keep an eye on her and possibly help with her situation.
Good luck with getting your first puppy and whatever you choose to do, you will always have friendly advice from us on this forum to help you
Best wishes
Mary