Using my teams as an example, I can hardly keep the total team salary above 120k.
Before you even talk about building a team, I'd say build your arena first. It's your main source of revenue and without it you won't have much funds to improve. For the record, it's totally possible to hit 20k in less than 3 full seasons, while you've just ended your fourth full season and is still below 15k (don't build more bleachers tho you've already got a lot). Focusing on building your team further will probably keep you stagnant for a long time.
That said, with you being relegated next season into leagues with 50% bots, and with your 120k budget, I'd say players with sensational primaries will be good enough. Don't really have to bother about secondaries until you can afford better players.