To create their price comparison, Idealo UK looked at 40 IKEA products which can be found in 33 different countries. They also compared prices both with and without VAT, since that additional charge isn't included in US products purchased in US stores (a point that actually makes a big difference).
Cheapest IKEA prices: Poland
Mos expensive Ikea prices: Australia
The United States is the third cheapest country for buying IKEA's products. But, as the study points out, this is a bit misleading. "Taxes for the USA aren't included in the IKEA pricing, as there is no federal sales tax in the United States. So unless you're shopping IKEA in Portland, Oregon (no state or local sales tax), this ranking is too high ... Based on the average sales tax (state and local) rate for 15 U.S. IKEA locations (7.02%), the U.S. IKEA price in our comparison would rank 14th, between France & Hungary." In fact, shoppers in Portland, Oregon — with their 0% sales tax — are paying the lowest price in the US for their Pax wardrobes and Billy bookcases. And they're third cheapest in the whole world.
Check out more of the Worldwide IKEA Price Comparison at Idealo UK.