Instead, I ordered some Eldoncard INC Blood Type Test cards from Amazon. $32.99 for a 5-pack or just over $6.50 per kit.
They were easy to use and I quickly confirmed I was O+ and will start including this as part of my emergency contact information. I also tested my 13 year old daughter's blood type and she was also O+. Given that my wife is O+, it is extremely unlikely that my 14 year old is anything but O+, but it would be pretty easy to check.
All in all it was money well spent and a fun little exercise to do at home. Of course, if I do not use the other 3 kits, it works out to $16.50 each for me and my 13 year old to verify our blood type.