Yeah, I'd say leveling up is essential to move ahead. But I'm with you on not wanting to put any money into the game... at least not my own. At first I did, of course, by getting a starter pack, a booster pack, and various cheaper beta cards from the market. All together it cost me $25 which I thought was okay, but really the limit of how much I wanted to spend. From then on I only used the money I got from selling reward cards (some of them for pennies, other for a nice chunk of dough), as well as the money I got from steemmonster posts, like this one. It seems to work all right, and not just for me. If you check out @itisjustme's experiment, she's doing the same: started to play from scratch last season, trying to get ahead without putting extra money into it.