I haven't used Comic Connect in a while, about 6/7 years, but they were OK shipping to the UK., about 3 weeks in total. Cost for slabbed books back then was just under $40, the book only cost $56 at auction, so it depends how bad you want it.
Shipping on raw books was I thought reasonable, I won 6 war books which cost around $18 to ship.
Insurance in relation to the books value will obviously push up costs, and obviously inflation etc has altered how much you pay.
As stated they're pretty helpful when you have need to contact them, and replied pretty quickly, BC (Before Covid) so, it may be a little different now.