I'm not sure asking them to make an offer would be a winning tactic.
I mean, if i was the buyer, i would be negatively impressed if the seller doesn't have a price tag in the mind, and i would think "mmh he wants to know how much i'm willing to pay so he can counter offer with a unreasonable higher price!" then I , as buyer, would have two possibilities: offering a low figure OR offering the fair one with no intention to increase it.
The best strategy (IMHO) is to be honest and think "what is the amount i would feel fairly satisfated?" and then ask for 1,5/2x of this amount.
For this domain i would feel satisfated for a $150-250 sale.
Last suggestion: edit your post and make your domain as unrecognizable by search engines, for example Click / Travelling () com . If the buyer would search this domain on Google (and i assure you they DO), his valuation would be influenced by the thread.