Personally, I had a 10/10 experience with Ship Sticks. Was heading to TPC Sawgrass and it was a group trip, so one of my co workers said we should just ship them out instead, and luckily we found out that Ship Sticks offered group discounts. We all got a really good price and decided to drop them off at a FedEx near the bar we usually head to after work. The guys at FedEx know how to put the labels as best as possible to our bags, and mind you one of our guys even decide to order the Ship Sticks box which we thought was kinda stupid.
We got to TPC the following Thursday and all of our stuff is there, and I had very little faith in them as I always checked my bags at the airport but I had a pretty crap experience last time I did that (but it was Spirit so that's on me). Everything was in the same condition we sent them, and for some reason our guy who sent them in a box made me want to buy one right after. We sent them back and I'm glad we did because all I brought back on the plane was my backpack. I'd definitely use them again, and I don't know but the prices for us justified based on the experience, might start using them for luggage to be honest.
I'd say the only thing I would do to make sure I get a lower price is sub to those guys, the emails aren't too spammy but legit every 4-5 weeks there's always a discount code sent which makes us want to travel more.