Undercutting by 1 Gil is the most respectful way you can list your item without cutting into the other people's profit by tanking the price.

And please let's stop the upvote farming narrative that you tank prices for the buyers. If you can tank prices that hard because some one undercut for 1 Gil without massively hurting your profit, you could have already set your price that low in the first place. You just care about your profit until someone undercuts, then it's just tanking out of spite. Helping the buyers is just a convenient excuse to justify Gil baron flexing.