I don't even think he spent £10m on all of them put together, let alone tens of.
One of the main reasons he struggled was not having the money to rebuild Moyes squad which was on its last legs (Moyes knew that as well, he was on the verge of yet another rebuild), but with no money. Which is also the reason Martinez was appointed, to work on a tiny budget.
The worst 2 things that could've happened were 1. Kenwright telling the world Martinez promise (Martinez looked embarrassed when he said it, because it was a long term goal, not something to be achieved overnight) and 2. Having THAT season straight off the bat. Set completely unrealistic expectations for his entire tenure.
But the positivity he brought back into the club was something that we miss massively.