The early Honda GL1000 Goldwings are a great bike. The first three years (1975, 76 & 77) were the best. Also, those years were considered the best looking. They were the second fastest production bike at that time. Only the Z1 was faster. They are somewhat heavy, but have a real low center of gravity so they don't feel heavy. That attribute makes them feel real solid when touring. Wind gusts don't have much of an effect. The last two years they made the GL1000, which was '78 & 79, Honda changed the cams and tuned them for more low end torque at the expense of high end performance. They did this to cater to the new "Touring" market which was just getting going for the Goldwing. Unfortunately, they also modified the styling of the bike in '78. Most opinions think it was for the worse.
I had a '76 GL1000 LTD. I didn't like the bike for in town commuting. It was a handful in stop and go traffic and heavy, but out on the back roads and highways it was great and a lot of fun. It loved to be thrashed and didn't miss a beat
. Prices vary based on condition, but prices go down as the year goes up. The '75's are starting to get hard to find in good condition and prices are higher. The 76 GL1000 LTD's and the Yellow '76's are the next in line for prices. '77's are next. If you can put up with the visual look of the '78 & 79 model year, they'll be the cheapest. Beware of bikes with aftermarket fairings, either mounted or formally mounted. They make a mess of the wiring harness. My advice is keep the bike "Naked".
As far as reliability, a well sorted GL1000 is mostly bullet proof. Timing belts are no big deal and should be changed about every 5 years. Carburetors on a bike that's been sitting will need to be gone through and cleaned. These bikes need to be run. They don't do well if they've been sitting. Other stuff to look out for is pretty common for most bikes so that should be nothing new. Cam chains can get noisy on higher milage bikes, but it's nothing to worry about. The chain is usually noisy at idle, but quiet down once the bike revs go up.
Hope that helps.