Not sure what size you are after, or whether you have a preference on makes at all?
I've tried an enormous amount of makes, I did used to very much like La Passione, and still have a couple of pairs I really rate, but I think they have cheapened their materials and pads a bit in recent years.
I tend to play safe now, and for me (ymmv) the Castelli Progetto X2 pad is simply a reliable and VERY comfortable pad - it's just key to get the right size, and nab something in the sale - I wouldn't pay the full price of around £160.
The Endurance 3 is at Winstanley for £89.99 (Weirdly Small is £98) which to my mind is a very good deal:
https://winstanleysbikes.co.uk/castelli-endurance-3-bib-shorts#172=295&173=168
I have a pair of the Pro Race ones as well - again grabbed in a sale, but the Endurance ones are arguably a better short imho.
A lot of people highly rate the Castelli KISS pad (found on their cheaper shorts), but for me, it really did not work - I'm a smallish build (Usually buy Castelli small kit) although currently a bit over what I should be at 74kg, I still wear small shorts. Ideally I should be hovering around the 70kg mark.
Another worthy mention that may be available around £100 would deffo include Lusso bibs.
I'd also not personally buy 2nd hand shorts, as you don't know how people have treated them, what they have used to wash them, and at what temperatures etc.