angular contact bearings for mill/drill ballscrews

I am reworking my CNC'd mill/drill. I set it up over 5 years ago and have learned a lot
since then. I never did replace the thrust bearings for the X and Y ballscrews. My mill still
has the originals- balls captured by a stamped steel retainer that are purely for thrust. I
would like to replace them so that they can handle some side load (mainly from timing
belt mounted motor arrangement). My day job has me sometimes sourcing ballscrew
bearings for real machine tools (Barden matched sets @ $375 a set) and I know I can't
afford the 'real thing'. I am interested in angular contact bearings that are affordable.

I did a quick search through this list and DIY_CNC and didn't run across any references to
this. So... What are people using for replacing the bearings on the endcaps on these mill/
drills?

Thanks,

Dan