I buy toys for all ages my hubby always say I spend too much.
For 7-9 mths, I go for those toys with no small detachable parts, preferably big in size, and are tactile. eg shape sorter with big pieces, beanie bags.
Towards 9 mths, I will start to get toys that move when something is done like bead chaser, pull alongs.
I usually dont't buy those electronic type of toys. My kids tend to be play with them for a short while then stop altogether. Learnt that painfully with my 1st child. I go more for toys that are versatile and can be played in many ways
My son loves playing with his elder sis's kitchen set after he turned 1yo.