Well I was relegated after season 12. I was a bit too fast promoting. I started in season 10 in division IV.7 was undefeated the entire season, then went to division III.6 where I unexpectedly won and was promoted to II.4. There I had a MASSIVE income and spent every cent fighting to survive, a battle that went down to the last week of the season. So when I was relegated I had the team I had with no money at all and had to sell Peni Lucas my draft pick to stay financially afloat. My income was much WORSE than my first time in division III despite a much bigger stadium. My season ticket holders had abandoned me in droves. I had another undefeated season but despite thst made no money for then two seasons in a row. I should have sold some guys and tried to win with a lesser team but prices started going crazy about then. I had bought at the peak, when 30 year old big men with proficient skills were $600,000 and my expensive players were rapidly becomming worth much much less.
So while you still have the revenue I would try to fill your tean with effecient but cost effective players. If I was suddenly faced with relegation I would trim my team down to this:
PG - 3 trainees at least one who can be good in the best game of the week. 5k, 10k and 20k.
SG - Solid starter 30k.
SF - this is the most cost effective position and one where you can dominate the others 40k.
PF - but weaker on the primaries and better on the secondaries. A PF with good JS, JR, OD and PA will be as effective as one twice his cost with +2 in all primaries but all atrocious secondaries. 30k.
C - May have to spend bigger here as you will want someone with great primaries so you can LI yourself and defend those that want to LI you. 50k.
A backup swingman who can play all of PG, SG and SF but max 10k.
A backup bigman with good secondaries so a PF not a C. Max 10k.
That seems low compared to here but that is 200k and I think that would be all you could afford and still make a little money so you could buy one more guy for the playoffs if there is an injury or you need a boost against your biggest rival. Be aware that there are some division III teams with much higher wages than this, but I don't know how they do it.
There must be others that have been relegated who can recount their experience. I just know I bounced down and did everything to bounce right back.