I've posted this before, but I recently bought some Gaia II myself. Cheapest place I found (by quite some margin) was
eBay, a seller called Stereoland, based in Romania.
Brand new. 2 sets. Arrived as promised and no issues or import duties.
I can recommend this seller based upon my own experience. No connection to seller.
Whilst I'm not familiar with Gaia I prices, I've just had a look and the seller has two sets, new and delivered for £889.