Those look like nice pots on the links you provided, but the estimated shipping is way too much for my zip code. I have a friend that uses huge pots, because she said the roses think they are in the ground. I don't know how many gallons they are, but I will ask. The black pots might not be as attractive as other colors, but they don't seem to crack like the others. My friend buys them in wholesale quantities from a local supplier. Sometimes she gets them from her gardener for free after one of his clients buys a small patio tree and doesn't need the container.

I wouldn't go for anything smaller than 20 gallons if I intented to keep an average sized HT rose potted for more than a couple of years in a warm climate.

Thank you for your advices Jasmine and Nik. I think the resin whiskey barrel from Home Depot may work.

HomeDepot (22.5” w x 15” h) $19.98

http://www.homedepot.com/p/22-1-2-in-Dia-Rustic-Oak-Resin-Whiskey-Barrel-Planter-with-Iron-Band-HDR-023395/205626595?MERCH=REC--NavPLPHorizontal1_rr--NA--205626595--N

For long term pots I always check out Costco at this time of the year. This year they have resin pots that look like whiskey barrels. Also, check out videos by Kittie Belindez on maintaining potted roses and maintenance: https://www.youtube.com/watch?v=OOiWKTryTHU 

I've been growing roses solely in pots for about 3-4 years now. Being in Australia, I don't have much advice on cheap pots, but I would second Nik's advice that bigger is better. I mostly start mine off in the smaller sizes, then go as big as I can get, depending on the rose and how fast it grows- the biggest pots in use at the moment are about 45 cm (about 18 in, but they sell them by diameter not gallon size here), I'm long overdue for another upsize on quite a few of my roses. Haha and I already have a shed full of smaller sized pots...

When ever I pot up, I'm rewarded by an extra flush of growth- they're a lot happier.

Not sure of your weather patterns, but I've noticed that during our hot spells, the black pots (especially ones in direct sun) soak up the heat - they are sometimes almost uncomfortably hot to the touch - which cant be good for them. I'm trying to rotate out the black ones, inconvenient as it is, as they tend to be the most easily available and the cheapest.

The smaller pots also dry out twice as fast as the large ones.

The other issue is that potted roses are so much more dependent on you for all their care..that means more care with fertilizer, watering, decent soil..etc etc..and judging by the ones in my neighbours yards, they wont ever get quite as big, or floriferous, as they do in the ground. Good luck..its a learning experience.