Just checked out that site, seems a lot of the Advance loco sets are sold out/long sold out, unless they carry poor stocks of them that would suggest they are quite popular or at least in Japan 
On a related note, I've been wondering if the Tagamoto range of motorised cars would be a good contender for use on an Advance layout (on the road track part of the layout of course). Although they are not quite small enough to be Advance scale they are not a mile off being around half the size of an equivalent Tomica diecast car. Add to that the light/sound effects which can be triggered by barcodes you place on the track I think it could be a nice addition to any layout.
On a related note, I've been wondering if the Tagamoto range of motorised cars would be a good contender for use on an Advance layout (on the road track part of the layout of course). Although they are not quite small enough to be Advance scale they are not a mile off being around half the size of an equivalent Tomica diecast car. Add to that the light/sound effects which can be triggered by barcodes you place on the track I think it could be a nice addition to any layout.