Well, I would guess that with the proceeds of selling Quigley and Salas, you could have enough money to buy veteran, trained players, and promote the first season after you do that. But it depends on what you really want to do, and how you enjoy playing Buzzerbeater. Do you like the process of training young players, and seeing them develop, getting little green arrows on Friday morning? Or do you like finding cool player builds on the TL, assembling a team that can execute particular tactics, and going for wins first? Now, neither approach is completely exclusive of the other (cause you'll be buying players, and working on winning even if you're a trainer at heart, and you can train players even if you're a veteran first team), but at some point, I think you personally have to decide which gives you more enjoyment. Once you do that, then it's time to decide some things. And don't listen to people who say you can't train in D5. That's nonsense. D5 is one of the best times to train players, cause your typical trainee starts off about as good as most D5 regular players. And after one season of single position training, your trainee will be better than most other players.
If you like trainining, there's no way I'd ever sell Salas and Quigley. They are excellent looking prospects, and they are both your "home" players, being drafted by you, or on your initial roster. As their salary grows, so will their merchandise value, effectively reducing their salary. So continue to train them in inside skills, and they'll make a great center and power forward duo for you for a long time to come. Don't forget to give them some other training as well, like 1v1 and passing. That will improve their performance but not cause their salaries to skyrocket. But after those two guys, it's not clear to me who you are training along with them. If you single position train them, and give each of them a full 48 minutes in a game, you have space for another trainee. Who is that? If nothing else get a decent guy to take a few of the minutes (especially in rebounding or 1v1 weeks), then sell him to make some extra money.
That brings up the rest of your roster. Right now it seems a bit too young, and my suggestion would be to sell those guys and buy slightly older players who are more completely developed. You clearly need more outside defense, and passing. So look for some guys who are 27-29, with OD in the ~10 range, and PA ~8. Those guys should be decent enough to put you over a lot of D5 teams, and help you stick around in D4 when you promote. So after the playoff eligibility deadline comes, look for some bargains in guys with salaries in the 8-10K range, and look for some decent secondary skills (e.g., inside shot and inside defense in the 7 range can be very useful for guards).
Lastly, I'd suggest not playing so much full court press, as it's usually not very effective against real human teams.