Most aftermarket are expensive $4-6K unless you can find a used one. Westendorf makes loaders for many tractors but you might find a Kubota dealer will install an OEM one for similar $.
Based in Onawa, Iowa (United States of America), Westendorf manufactures front end tractor loaders, buckets, scoops, shade canopies, snow plows, hay equipment, wagons, box scrapers, spreaders, bale spears, attachments, & ATV & skid steer accessories.
I had a Koyker loader on my Mitsubishi tractor. It was a great loader. They're made in South Dakota. They have a range of sizes and could probably recommend the correct size for you but be prepared to pay $5000 or so. Another option would be to go shopping for a tractor that has a loader and sell your old one.