It's a lot of work, but if you do the research and are willing to learn a little by trial and error it's definitely worth it in the end, but you have to be committed to it. You don't need a license to get 99% of the products you need to keep it healthy. Just about every product you need (fungicide, fertilizer, insecticide) is available in one form or another that can be bought at home depot you just need to be willing to read labels and do a little math to dial in the application rates. The only difference between the product you need a license for is the concentration of the active ingredient.
Construction took my brother and I
about 3 weekends and cost about $2500 including excavator rental, drainage pipe, gravel, irrigation parts, used John Deere greensmower in great shape, and the sod for the green (creeping bentgrass) and the rough surrounds (k blue, fescue mix). Annual upkeep is about $500 maybe slightly less depending upon how realistic you want it to play. I cut this at .140 inches to keep it rolling around 9 on the stimpmeter, 10+ if i roll it regularly. If you'd be happy to have it run 7-8 you can cut it a little higher and the upkeep is a bit less demanding. A lot of it also depends on how well the growing conditions are. Poor conditions mean more spraying, aerating, etc... which means more $. If you wanted just a target green for chipping into that was kept at fairway height (.350 inches roughly) you probably could have a nice surface without the drainage and irrigation which would cut costs dramatically and still look nice in the back yard.
Here's a couple more pics,