Drat.
Well thrift stores tend to have good prices on sewing machines, if ya have that much motivation behind it.
Otherwiseeee, there is this, which may work, but be a bit snug!
It's super fun! I would definitely give it a day to air out because the smell is pretty strong, but putting some treats and catnip in it is great way to get your little guy used to it.
Here's the link where my mom got it: LINK
This is the one I bought.
An awesome gift I got from my mums: Amazon Link
Off brand one from Amazon
Walking might be difficult - as everyone else said, you've got to make sure your cat is comfortable in the harness and can't slip it. Cat getting loose on the street corner = disaster.
Secondary option! Cat backpack!
https://www.amazon.com/dp/B01FNJWPOG/?tag=petcomn-20
Lets your cat get outside without risk of escape, and might be a good way to acclimatize them to being out in a loud area. We have this one for our cat and use it to get him to/from the Vet, when we move, and occasionally train travel. Only comment I have is that it's a little smaller than the pictures suggest - he fits just fine, but there's not a lot of room to dance around in there. So if your cat's chunky, maybe look for a bigger one.
The cat should be in one of these to separate it from other pets
Name: "Backpack Pet Carriers"
$60
Amazon Link:
https://www.amazon.com/Texsens-Innovative-Traveler-Backpack-Carriers/dp/B01FNJWPOG