.22: Nikon makes a great rimfire scope for about $100 you can get on Amazon.
.223: Primary Arms: either get one of their fixed 3x scopes or the 1-6x with the ACSS reticle. $200-$300. If you go to their showroom, a lot of times they will have blemished models for a discount.
Saiga: either a Sig Romeo5 or Primary Arms micro dot. $120.
Others can probably give you better recs on the RPR than I can, so I'll leave that one alone.