I love my 301A! You got yours for a steal!
The bobbins should be either Singer #45785 or #A1225 (the website says they are alternate part numbers).
Looking at the photo, you have the bobbin case, and I don't see anything missing, so you should be good to go
Looking up the part number reminds me that I needed to find a new walking foot, since a piece of mine broke recently (still usable, but the plastic is a little brittle, so I should replace it before I need it!)