A makeshift Reds side including youngsters Rhys Meynell, Scott McGrory, Michael Coulson and Luke Potter also contained Brazilian trialist Dennis Souza, as well as returning Lewin Nyatanga and Mostto on the bench.
The Reds took the lead on 20 minutes when Kayode Odejayi netted his fourth pre-season goal in three games. He cut in from the left and fired past Buxton keeper Hartley.
Buxton equalised before half time when Paul Walker scored from close range.
Simon Davey rung the changes at half time with Mostto coming on for his first appearance and Nyatanga in his first return appearance.
Rohan Ricketts then set up Istvan Ferenczi on 50 minutes to put the Reds back into the lead but Mostto stole the show minutes later.
He received the ball and moved forward before unleashing a super strike high into the net past Hartley.
Reds Side: Letheren (Colgan 45), Togwell (Johnson 45), Potter (Werling 45), Meynell, Souza (Nyatanga 45), Devaney, Mattis (Howard 45), McCann (Ricketts 45), McGrory (Heslop 45), Odejayi (Ferenczi 45), Coulson (Mostto 45).
Mostto bags on debut