No idea whether he was his son..?
Possible cost of his training depends on what kind of ‘doctor’ he became. There wasn’t really a concept of doctor as we understand it. You were either a physician (highest rank, attended elite universities, considered fully gentlemen, equal to their wealthy clients — whom they never touched! ), a surgeon (intermediate rank, viewed as tradesmen, trained via apprenticeships, set bones, treated wounds, doing surgery), or an apothecary (lowest rank because they had physical shops, mixed drugs, trained via apprenticeships, though in practice they often were surgeon-apothecaries in small places).
Like when Jane is ill at Netherfield, Mr H (not Dr) Jones the apothecary is called from Meryton , but the Bingley sisters are convinced no country advice is any use and want to send for their London physician. Physicians would only practice in big cities or fashionable watering places like Bath.
Mr Perry in Emma, is also a smalltown ‘apothecary’, but presumably also a surgeon, and as he’s clearly the only medic in town, he sees even the elite of Highbury. We can see how well he’s doing financially, as he’s planning to buy a carriage, which was a sign of a significant income!