This is a tough one for me. Most of my gear is mid price stuff - Epi LP, PRS SE, Fender Korean Tele, Pacifica 812, Laney TF300 amp. However, I also have a two slightly higher end guitars - a US Fender Strat and a Warmoth Soloist. I've found that I have spent quite a bit of money on some of the cheaper guitars, trying to improve them.
The Epi has had a refret, 2 sets of new pickups, tuners and electronics, bringing the total spendon the guitar to well over £750. Similarly, I've bought new pickups and tuners for the PRS, and it's going to need a refret soon, because the fretwire may as well be tinfoil, it's so soft.
Neither of the two more expensive guitars have cost me anything in changes, but then neither has the Pacifica or the Tele.
It's a tough call, and it does depend largely on the individual piece of gear, but there are certain guitars I own that I wish i had waited on, saved more cash and bought something of higher initial quality, soley because I've ended up spending more to bring them up to scratch.