Believe me when I say I full recall beginning in photography and what it can cost. If you get "serious", this is not a lightweight expense. Good optics cost money.
But, then again, my suggestion is ... if you get serious, you should consider a Full Frame. I mean, chances are you will eventually arrive at this decision, but if you can cut to the chase ... so much the better. Save yourself some money doing the "baby-step thingy."
It would have saved me three years of putzing around with APS-C sized sensors and all the tom-foolery that goes along with it. The a100 and the A700 cost me $2500, together, when I started. Going straight to the A850, right now ... $1999. Hey, hind-sight is 20-20, right?
So ... I give that costly experience away and say ... "Full Frame ... it is the wave of the future and can save you a few bucks along the way."
For what it is worth.
This is an equal opinionated forum, right? Opine!