I'm a newbie transformers collector too, but based on my [rather limited] experience, I think it's safe to say that transformers is definitely one of the "more affordable" toy collecting pursuits available - assuming you steer clear from those super exclusive MISB made in 1984 10/10 condition G1 toys complete with certificate of authenticity.
If you stick to the regular stuff that Hasbro makes, you shoudl be fine.
Even if you buy the occasional masterpiece that would set you back by $250, that's fine too - relatively speaking of course.
Before getting into transformers, I used to collect 1/6 figures (Hot Toys, Enterbay etc.) and $250 is pretty much the standard price point. The thing is, new figures come out every 2-3 months and that situation is simply untenable for me. I've sold off most of my 1/6 collection and in fact i've decided to even cut back a little on transformres.
Waiting for Hasbro Masterpiece Grimlock nowfingers crossed.