Well you should take into account that the season is almost over, so trainees on the market now have already had almost a season of training under their belt, so you can deduct about 10 SP if you want to compare it to what amount of skillpoints they'd have had at the start of the season. So 153k for a HoF with 41 badly distributed skillpoints isn't too cheap, though not expensive either. I do think your purchase was a but expensive, because you can get an 18yo PA with about 50 TSP for 50-100k after the draft.
That one looks pretty nice, though I think it's still a lot of cash to spend on 1 trainee when you've just started to play the game. As said, your arena is very important because it generates your income, and without a proper arena you can't field a good team, so winning is harding and filling your arena is harder too, resulting in less income and so on and so forth. If I were you I'd target Superstar potential trainees, those can be bought for decent prices of around 100k and can be trained for a very long time too. Then you'll have some cash for your arena and some to spend on veterans to help you win now, to fill your arena.
So yes, I do think you need to keep expanding your arena because you'll need it anyways, and if you buy 3 vets of around 10-20k salary I'm pretty sure you'll win more than half of your league games if you manage gameshape and enthousiasm properly. Then your arena should be filled while you can maintain standard pricing (10-35-100-800) or maybe higher prices.