I used this https://www.amazon.com/gp/product/B00XWQSD7G/ in the past; at the moment it may be slightly over-priced.

If I was buying it today then probably one of these:

https://www.amazon.com/Balance-Breens-Alpha-Supplement-Capsules/dp/B08VR94LZ6/

https://www.amazon.com/Capsules-Vegetarian-Supplement-Supports-Horbaach/dp/B0852MXRHN/

After my first couple bottles A-GPC, then I only ever bought powder.