Are you mechanically inclined at all? I purchased a motor conversion kit and a battery to convert my regular bike to ebike. It wasn't really a difficult process, the hardest part was removing the bottom bracket as it was quite stuck. Took some thinking to get enough leverage without having the tool head chew out the bracket teeth. The rest was relatively plug and play. I was able to get the 500 W motor and 48 V 18 A hour battery for ~$1200 CAD together. I use it to commute to work so I wanted a longer range, if you don't need as much power or as much range you could do it for cheaper.

I went for a mid drive motor which are more efficient but more expensive than hub drive, if you're budget conscious you could do a hub drive. From my understanding the hub drive can be more difficult for maintenance (the wheel is a special version, so you need to buy another wheel that works with the hub drive if any issues occur) but I'm no expert.

All of that is a moot point if you don't already have a bike to use, but you could find a local bike recycle store to get one cheap? Or you could get a new bike and convert that. I had a marin fairfax 2 that I converted over and it works great, haven't had any issues and I've put on a couple thousand kms on it since converting (the display tracks total distance which is handy). I believe the marin was $700ish new from my local store.

https://www.amazon.ca/dp/B083J95GJP?geniuslink=true&psc=1

https://www.amazon.ca/10AH-Electric-Bicycle-Lithinum-Battery/dp/B09C1RP9KV

You could search for other options if you don't want to support amazon, there are different sites to source the parts from, those were just the first two that I saw.

https://ebikes.ca/shop/electric-bicycle-parts/batteries.html?___store=canadian&___from_store=international

Here's a battery from a Canadian company.

https://lunacycle.com/no-drill-battery-mount-kit/

Here's a mounting bracket for the battery if the bracket seems unsteady or the holes don't line up like with mine.

https://www.aliexpress.com/item/1005005664281095.html?pdp_npi=3%40dis%21CAD%21C%24+818.29%21C%24+572.80%21%21%21%21%21%402103205316878009193475419ef97f%2112000033941099570%21sh%21CA%213139937923

This is what I ended up going with. Let me know if you have any questions, I'd be happy to chat about the process more.