Simpson is working with a squad down to the bare bones as a result of injuries to a host of players, although the latest news suggests some are not as bad as first feared.
He told ShrewsPlayer: "I'll be honest, we did try. I've been trying for the last week or two to get players in but the ones I wanted weren't available for one reason or another and I've decided there's no point bringing players in just for the sake of it, for us to develop somebody else's young player.
"The ones who were talked about, I didn't feel were any better than what we had here. Also, we've decided to go down the route of bringing in four first-year pro's to try and develop them and bring them on, getting the YTS boys involved in training with the pro's.
"I don't want to stop them from coming through, I want to give them an opportunity. Whether it's as a sub or as a 19th man travelling, I think they deserve a chance. It leaves me with only 18 for this weekend but I only need 18, I'm going to go with what we've got."
He added: "The transfer window for permanent deals is closed, the loan window reopens again in a week's time so we just have to get through this weekend. If our luck carries on going against us and we get another horrendous injury this weekend then we'll have to look into the loan market then."