recommend a decent bass amp sim plugin please - cheaper the better

JMP220478

as above - I'm on Reaper on Mac OS  10.15 ( older mac ) 

looking for a good rock tones primarily .

cheers in advance 

steamabacus

The free bit of Amplitube (you buy extra amps via online downloads) has a bass amp, also a 'Marshall' and a 'Fender'. Also you can mix and match preamp, poweramp and cabinet components of those three - I once got a great rock bass sound (DI'd live gig recording) using the bass preamp and cab but the 'Marshall' power amp cranked full up.

IMC1980

https://www.igniteamps.com/#shb-1 this is worth a look, you'll need some IRs to go with it (free IR loader on the same page: https://www.igniteamps.com/#nadir), but a quick Google search will turn up stuff like this: https://shift-line.com/irpackbass

guitarfishbay

https://www.tseaudio.com/software/tseBOD

Free Sansamp style sim

Stratavarious

I just DI then use some compression (ReaComp got a rock bass setting), EQ and then load bass cab IR files into Reaverb.  Very versatile using IRs. 

But I’ve used the free Bod plugin suggested above if you want more colour/grit.

PolarityMan

parallax or mammoth

Vintage65

The Plugin Alliance Ampeg amps are good, and they are the same as the UAD ones. There are 4 to choose from, but try to buy in the regular sales. Once you are a customer you get loyalty vouchers, and I never paid more than $19.99 and sometimes cheaper than that. They do a 14 day trial, so check them all out!

https://www.plugin-alliance.com/en/products.html

pintspiller

I use a Plugin Alliance Ampeg and its great. I also swear by Bass Professor II by  Sonic Anomaly but I think it may be Windows only.