>>58121016
You're not going to have much luck with finding 151 packs at retail, I've seen a few pop up recently but it's rare. You could certainly buy singles, maybe if there's some specific Pokemon you like you could collect specific cards for them for example instead of just sticking to 151. Websites like Pokecollector have a good list of cards to look at, so see what you like.
>Is this a good time to start ocllecting?
I don't think there's been a good time to start since Covid.
>Where do I start?
Have a look at the FAQ in the OP. Get yourself some decent protective sleeves and a binder for your good cards, you don't need to sleeve commons unless you want to display them in the binder. When buying cards a good ballpark for value is to check recently sold listings on eBay. Make sure you look carefully at cards you buy, look up how to identify fakes (shouldn't be a big problem buying from professional sellers but worth it if you're ever looking on things like Facebook Marketplace).