£30 gets you lightly used good Shimano SPD on Evilbay if you're not in a hurry.
XT or XTR if you get lucky though they usually got £35-40. XTR are indeed slightly better to clip in/out of (it's not just marketing BS I have a set) but M540 are serviceable (with a shimano tool) and can be had for £20 lightly used.
£30 gets you lightly used good Shimano SPD on Evilbay if you're not in a hurry.
XT or XTR if you get lucky though they usually got £35-40. XTR are indeed slightly better to clip in/out of (it's not just marketing BS I have a set) but M540 are serviceable (with a shimano tool) and can be had for £20 lightly used.