While buying directly from VS would be convenient, I've found that the current system works better - because often I'll find good deals I wouldn't have known to search for, once at the location. I spend more on impulse buys from the shop I get teleported to than I do on the items searched for, typically.
As for shard merger, I could see a way of doing it rather cleanly, though it could cause some player towns to get scrambled together.
First (and the largest cost), would be to redraw and reprogram the maps to be 1" (1 minute of a degree) per step instead of the current minutes 4-5 per step. This would increase land area by 16x. Some new roads might need to be added in some cities (imagine Luna and Zento with two ring roads instead of one - with all the lots now capable of handling 18x18s), while additional space would be added as many of the cities with walls would not actually increase the thickness of the walls by 4x in the redrawing, and the NPC shops themselves would not need enlarging.
Then, take the 4 being merged, and catalog all their unique spots and statics - copy them over (in some cases, to be side by side with stuff from other shards). Now, the world is ready to be populated. Some stuff that is tied to old EM accounts, or was a blessed location once belonging to a deceased player but is considered special to the shard population, might have to be moved over manually or recreated.
Third step, have the housing server "pack up" every house on the servers. When the account logs in, the player has the option of placing the house and its contents within a degree or so radius of its original location on the new map, possibly in a reserved 1/4 of the equivalent area for a specific set of immigrants from the same shard (a clearing that was 20x20 (400 squares) on each old shard, would now be 80x80 (6400 squares), and could be divided up into 4 40x40 (1600 square) regions designated for each shard). This would not only reduce the chance of griefing through house placement, but give the homeowners room to resize their houses later.
For the first 90 days, no new houses can be built, and (as a safety precaution) no houses could be demolished (though they might be movable via repacking - the packing up system might actually allow house relocation after the fact - especially if a GM has to come in to fix a housing dispute).
After everyone is given 3 months to settle in, then the remaining new open space would be opened up for house expansion and new placements. Any houses that hadn't been placed would be left in storage until such time (if ever) the player returns to re-place, and can be put any place it can legally fit.
If a house not replaced (still stored) has its account go to the point where the house would have gone IDOC, 6 months after the merger, its contents go into a raffle (a few houses added each day), each ticket capable of winning a container from the house (with all non-containers from the house being put into the moving crate, which would then count as 1 container for every 100 items). Raffles will be totally blind (other than the number of containers/tickets being listed), limited to 10 tickets per account per drawing (with each ticket after the first doubling in cost when bought by one account - say, 100k for ticket 1, 200k for ticket 2, 400k for ticket 3, up to 51.2 million for the 10th ticket) and the drawings occur an hour after the number of tickets sold for the house match the number of containers (though sales could continue up to 5 minutes of the drawing, so that some ticket holders get nothing for their ticket). You could end up with a bunch of rares or resources - or you could end up with a moving crate full of gozas. The doubling prices means that persons trying to speculate would be acting as a gold sink, as 10 tickets for one drawing would end up costing over 90 million, with no guarantee of a payoff worth that much.