A three-bedroom mobile home on the beach front in Abersoch on the Llyn Peninsula is up for sale at £500,000.
The £500k chalet is on the top of the dunes overlooking the beach
While one estate agent said the price tag must be a record high, they did not believe it would impact property prices because it is aimed at a unique buyer.
But Caernarfon MP Hywel Williams said the price was "symptomatic" of the pressure on the local housing market.
The vendors do not intend advertising the chalet as they say they have a waiting list of just under 100 people.
For their half-a-million pounds, the new owner will get sea views, steps down to the beach, French doors to a decked area, designer furniture and gadgets such as under-floor heating.
They would be able to use the holiday home for 10-and-a-half months of each year and have to pay £4,750 in annual site fees.
A second mobile home at the Warren holiday park has been put on the market for £475,000 by the Haulfryn Group.
Pwllheli estate agent Stephen Tudor explained that Abersoch is a popular tourist area - a property hot spot where prices had increased rapidly in the early 2000s although they have since stabilised.
However, the chalets at the Warren represented a "totally different and abstract" property market, he said.
The holiday homes have designer furniture and fittings
"It must be a record. I haven't heard of figures at that level for a mobile home, not even in Abersoch. That's certainly higher than figures achieved in the past."
But, he explained: "It's unique in its location and the facilities the Warren offers... Somebody else with a mobile home would not expect to see that sort of level."
Dafydd Hardy, director of Dafydd Hardy Estate Agents, agreed that the holiday home prices have little relevance to the local property market.
"People are buying them for holiday purposes, not buying them to live in full-time" he said.
"A local person would not want to buy a chalet on the Warren. It's a different market. If someone wants to pay that sort of money, good luck to them."
Andrew Sawyer, Haulfryn marketing manager, explained that the £500,000 price tag of the 42ft x 20ft chalet was due to its sought-after beach front location.
"We're pretty sure it's the most expensive holiday home in Wales of its type," he said.
Most of their customers are from areas like Cheshire and Liverpool, he said.
And far from harming the local housing market, Mr Sawyer feels they are helping it.
"People ordinarily would think they want to be in Abersoch and buy bricks and mortar," he said.
"If someone buys a holiday home with us they are not impacting on the housing stock."
But Caernarfon MP Hywel Williams said he knew of one young couple who had recently had to pay eight times their combined salary to get a mortgage for a "run-of-the mill" terrace house in Pwllheli.
Of the £500,000 chalet, he said: "This is symptomatic of the pressure on the market in the Llyn Peninsula.
"It shows the need for a housing policy locally which protects the local market so that local people can buy a house."