Yeah - Crystals are your best bet tbh.
BLM isn't really expensive until 51 I've found (pre 51, you won't need more than a million gil or so of kit to be 'good', after 51 you'll need 3 times that, and to be very good 100 times. (on my expensive server - Hades))
RNG is also excellent for farming the crystals. If possible, level in San D'Oria. Fort Ghelsba drops own for this. Orcs = Fire Crystals

, Funguars = Dark and Sleepshrooms

. Leveling from 1-10 can make you as much as 250K if you know what you're doing.
I have found SMN to be an extremely powerful job for solo'ing as well. Carbuncle is an {Impossible To Guage} Tank. (Come on - level 10 smn's Carbuncle vs level 7 mobs taking 0 - 3 per hit...insane...)