They're legit...Suzo-Happ's been around for many years now...they used to be known as Happs Controls.
They've been supplying slot parts for a long time.
Back then, I used to call the secretary at the office, to find out if they could reduce the shipping charges on one of my orders.
I didn't like getting charged 30 bucks for a piece of harness wiring in a box.
I asked her to just throw it into a padded bag from the post office and the shipping was no more than 8 bucks.
That was 20 years ago... I doubt they or anyone else would do that nowadays.
Shipping generally, has gone up quite a bit.... pretty much standard everywhere.