I don't really have any items with sentimental value, but the best ones I can come up with are my guitars. My Epiphone Les Paul because it was my first guitar from 4 or 5 years ago, I learned just about all I know about playing guitar on it, the headstock has been broken off and fixed twice and I've stuck with it as my main guitar (basses excepted). It's also got a look to it that isn't necessarily unique but you don't really see around on Les Pauls much anymore (Cherry red and cream finish, with a bigsby tremolo)
My Fender Geddy Lee jazz bass mostly because it's a fucking solid instrument that I'll probably never get rid of or stop using. I did just get pretty recently but it's one of the smoothest basses I've played and I'm proud to own it.
If anything else, I suppose my laptop because I use it excessively and it was one of the first larger purchases I made with my own money. It's quite outdated, the screen and battery are toast, USBs are fidgety, and it's by no means irreplaceable, but it's definitely a purchase I haven't looked back on