for the bassinette I have 2 sheets but I have a spewer so I put a cloth nappy under her head so just change that when she spews and her sheets every few days.
With the cot i have about 4 sets of sheets, but because we use sleeping bags for DD1 and will use them for DD2 when she gets bigger, Mum sewed elastic around the flat sheets off DD1's sets to make fitted sheets for DD2s cot
As for blankets for DD2 she is still wrapped so I have 4 stretchy blankets to wrap her in and a few to tuck her in when its cold.