Unless the £900 includes the cost of the season ticket I really can't wrap my head around the figures
Assuming a standard adult terrace season ticket: £230
Home & away shirts: £85
Away tickets bought through the club assuming average £20 each - £220
3 away tickets for middle 8s bought through club £60
In ground food/drink purchase if average £10 per game - £150 inc middle 8s
Coach travel £10 per away game (11 regular, 3 M8s, 1 Blackpool) £150
That gets to £895, so maybe it's not such a stretch, but not everyone goes to every game or goes by club coach so there's still some stretching involved
Oh wait, I forgot Blackpool another £20 for that so now £915