Cartridge

My son is trying Vinyl and so I bought him a Pro-Ject Expression II with a Pro-Ject speed box. The guy at music direct said the cart on the unit is garbage and I believe him after looking at it. My question is what would be a good cart for this set up. Carts I have looked at are Dynavector 10x5 and Clearaudio Beta. Are these any good or do you experts have any other suggestions. Also, the carts have to be MM or high output MC. I am not ready to buy him a stand alone Phono Stage.

It has been many years since I have been into Vinyl and my knowledge is very little. Thanks for all your suggestions in advance.