You can buy the fittings and the hose online or local. Most FLAPS* can get the fittings and the hose. Some stock it. Summit has some (vintage air and other manufacturers as well).
is correct that a lot of places can make hydraulic hoses, but many of them don't have the dies for AC hoses. The main difference is that AC hoses are double crimped. AFAIK, the diameters are the same, although some of the larger low pressure hoses are sometimes bigger than hydraulic folks deal with.
In a pinch, the dies for hydraulic fittings can be used, but you have to crimp once, reposition and crimp again.
You can also do a search for "mobile ac hose" or "mobile hydraulic hose" in your area. There are guys with the tools in a van, along with an assortment of fittings, that'll come out and make them on site for you. Most aren't as expensive as you'd think.
You'll spend way, way more on a good crimper setup with the right dies (you need at least two, possibly 3 or 4) that you'll pay to have someone crimp them for you.
I put my fittings and hoses together, wrap both the fitting and the hose with masking tape and mark with a sharpie so that the fitting is "clocked" correctly when crimped. Then take it in to my local NAPA that has the correct dies (and sells fittings and hose), and they crimp for me. If I buy the fittings and hose there, they'll crimp them for free.
*FLAPS = Friendly Local Auto Parts Store