400 miles is quite a distance to travel for a sit that is just a few days. If you happened to invite them, and they made this request, that seems a bit more understandable to me, though I probably still would not ask in this case.
If they are choosing to travel this long distance for whatever reason, whether it is specifically for your sit, they are hoping to spend time in your general region and your sit will get them going in that direction,etc…then I don’t think it is appropriate to ask this outright. If a sitter can’t afford the cost of travel for a sit, they should not be applying in my opinion.
I get the cost of gas feeling burdensome….I am currently sitting in California, which has the highest gas prices in the United States at all times, so prices now are particularly expensive. Our next sit is the start of our Northern California ‘adventure’ and is 6 hours away-we decided to fill up the tank on our last outing to go food shopping and it surely stung a bit!
I think it is kind of you to consider this, but please do not feel you are under any obligation. If you think you may have difficulty securing a sitter, and this person is your best shot, then it could make sense to follow through on the offer.
If hosts want to make an offer to contribute to fuel costs upfront, that is very kind of them and I think it would be totally fine for sitters to take them up on it. But for sitters that feel that hosts somehow should bear some sort of responsibility for their travel costs to the point of outright asking them, I don’t agree with that–again, if a sitter can’t afford to get themselves to a sit, I don’t think they should apply.
I get that costs have risen, and again, if hosts want to make offers for assistance, that is great. But I just don’t think it is right for sitters to ask–while it isn’t exactly the same as asking to be paid for the sit, it’s kind of in that neighborhood to me, and I imagine if you were to ask THS about it, they would likely say that sitters shouldn’t be asking for such things.