for T5 DIY, since you have a 2.5' tank but there is no 2.5' T5, so maybe you can use 2' tube for 4xT5. Parts estimated market prices: T5 ard $20, eballast ard $40-50 each. No. of eballest needed depends on the on/off combination you want. T5 spider reflector ard $15 (per tube). If you use acrylic to construct a simple hood ard $20.
to save cost further you can use the Elbiru eballast (no pre-heat) at half the price.
pls do the maths
have fun