Hard to say to be honnest. Depends a lot on your season goals. If you aim to stay in first div with no ambitions for continental football, you might be ok with the keeper. if you aim on getting continental football, its better to look out on the transfer market and buy something of 14 stars.
If i recall well, at the end of the end season transfer period, you can buy 34-36 year old keepers with great vallues for like 30. You can use them a few seasons and sell the mat the bank for 22 mil so you lose basically 8 mil for a few seaons. Way more interesting than renting players, right?
In my experience, the keeper is the most important player in the team.
But again, it all depends on your ambitions. If you wanna keep upgrading facilities and play between place 7-11, than you don't need to invest too much in great players because your aim is to avoid place 12. On the other hand, if you like to play for the continental spots, than you need to invest in players.
I always went for upgrading facilities and started investing in players and training/youth facilities when i had the max stadion. Its a slow approach but i enjoy now the benefits of it.