If your house temps are relatively stable you might be able to use a dimmer switch - they cost about $10 I think.
But you do get a zoomed repti-temp thermostat for about $25 and the ranco and johnsons are around $80 ish I think.
Think of the t-stat as the best investment you can make in your snakes long term health - I say long term because it can move from tank to tank with him as he grows.
dr del
Derek
7 adult Royals (2.5), 1.0 COS Pastel, 1.0 Enchi, 1.1 Lesser platty Royal python, 1.1 Black pastel Royal python, 0.1 Blue eyed leucistic ( Super lesser), 0.1 Piebald Royal python, 1.0 Sinaloan milk snake 1.0 crested gecko and 1 bad case of ETS. no wife, no surprise.