No "might" about buying the pins. Just buy and be done with it. Hard enough to get nice new lightly lubricated ones in, especially at the back. Old, crappy, dirty ones make life that much too much harder.
If your not experienced at this do the front ones first with the arch liner removed. Room to move and you can see whats going on. Not a bad idea to get a few of the liner fitting thingies too in case some break. I think I got five or six spares when I did mine and used them.
Allow time to sort out or make a tool for pulling the top pins out at the back. I'm surprised there isn't a "my really effective pulling tool" design floating around on-line. I rooted around and found something in the collection, dammed if I can remember what I used tho'. (40" Snap-On with middle section, but no top, and side cabinet all full with a 4 drawer filing cabinets worth of overspill equals plenty of scope for rooting.)
Forget the "Took me 10 minutes to change a bag stuck on a rock halfway up a mountain with a leatherman multitool" gloat liers. That one comes from the same list as Mr Haynes oft printed "simply remove .... " which must surely be high up on the most effective ever swearword generator phase list. I made the mistake of doing the back ones first. Took a leisurely summer afternoon to do that pair. Everything was stuck tight but it all came apart once I'd figured the right method of persuasion. Under two hours from pulling the bonnet release to do the fronts. Thoughtful amble usually gets me finished faster than the rush headed guys who have to take time out to fix the bits they broke due to hurrying!
Clive