I've replaced the lithium rechargeable in my Gshock once. It was quite easy I have to say but the buttons are fiddly. I got the battery off eBay for about £16.

I've replaced the lithium rechargeable in my Gshock once. It was quite easy I have to say but the buttons are fiddly. I got the battery off eBay for about £16. Straps are what give out first and I've been through about 4 where it's become unsightly or otherwise degraded.