There is another company in NJ called metal creations. I had them make me an alloy arch last month for $1400. Unfortunately shipping
was another $400 as it was 10.5' wide. Many of the local places were quoting $1200 deposit for materials and a finished cost of $2500 to $3500.
I'm fairly happy with the finished result, but am having about $250 worth of mods including welded front pads. All the premade towers come with adjustable mounts which seem to allow a bunch of sway.
An even cheaper option and maybe ok for some is a fish
on sports arch for $1100. One good thing about a take apart deal is you could sell it at some point on EBay for maybe 60 to 70% of what you paid if you want to remove it.
Other issue on a narrow stern monohull
is that you often need to replace the stern pulpit and integrate it into the arch which adds a bunch of cost.