I think not, Mo. His two aunts, Lady Bertram & her sister Mrs Norris, are comparing how much they had given him; whence we surely extrapolate that, when a visiting young relative left, it would be customary for his entertaining elder family to give him a cash present. So the £10 would appear as a smallish sum, appropriate to be given as a gift ["Sir Thomas said it would be enough"]. But nowadays £1300, even if given as a cheque, would surely be more than enough as a token farewell prezzie! It is true, as you say, that he was not a regular visitor, in the sense of dropping by every week or so; but I don't see that effects my main point about the current value of the sum quoted.