I've just raised this with DH, we travel extensively with work and for weekends away together.
He priced up his bag when he goes away for work, and even that touched £300.
We then discussed how we'd approach it with our friends and decided that it isn't that cut and dried.
Friend A -
Earns similar amounts, and has a similar total household income and expenses. Travel with them occasionally, would be absolutley mortified they'd lost it and would offer immediately to pay there and then to resolve the problem. Is generally a very concientious person.
Outcome - we'd say don't worry about it. Accidents happen. But would accept their help in sourcing replacements/their paying at the till whilst away.
Friend B -
Lower income, single parent. Generally concientious. A weekend away is a much saved for and needed treat
Outcome - we'd say don't worry about it. Accidents happen. Refuse any attempts at payment. Accept a drink as way of recompense.
Friend C -
Same as friend A, but very scatty and constantly losing their own things/damaging things of ours when at our house. But a lovely person.
Outcome - they wouldn't offer to pay, they'd laugh about it being "oh isn't that typical of me". Wouldn't ask for payment, would edge out of the friendship - they've shown they don't respect things/me.
Friend D - same as friend B. But with a bad attitude.
Outcome - wouldn't have asked in the first place. Wouldn't be friends in the first place.
So overall - I wouldn't ask for or accept payment from anyone because I'm very aware that these things do happen. I'd be annoyed, and gutted because I would have packed things I loved and spent time and money on. But life happens.