is Magento docker ready? can I use docker to deploy Magento 1.9?
alternatively, can I use Heroku?
Yes, Magento should work with both Docker and Heroku.
There are quite a few resources in Google for the images and documentations to set it up.
I recomndate you to use rackspace . Rackspace Inc. is a managed cloud computing company based in USA, they are magento platinum hosting partner and their customer support is best ever i receive in my 5 yr of ecommerce experiance. they provide chat and 24*7 call support. i have my many magento web store hosted on Rackspace << Snipped>>.
they are little costly but best in service.
I recommended Nexcess.net we are already using it. The best support system. Whatever you need they will do that for you. Even their respond time is pretty low.
They are Magento partner As well.
Try once nexcess.net
$500 is too much just for 4GbRam/10GB space. You have better options. Nexcess has $75 for same server size, but it is not VPS. Cloudways has similar pricing for their VPS packages. You can easily find a hosting for $100 or under that. Rackspace has quoted you a really high price. What are they exactly offering in that package other than server size?
I am currently performing tests with Aspiration Hosting (I have no affiliation with them) and I must say I am very impressed so far with their Plus Cloud Hosting package. It comes standard with 2 Core CPU, 2GB, 10MB/s disk I/O, LiteMage FPC, and CDN! The gain in performance has been huge, even though I am coming from another so-called "Magento Optimized" hosting company which does not even run LiteSpeed. I must say that Aspiration Hosting customer service is also top of the line: they even provide help from their Web Development department in order to assist you when you have issues.
It's a bit early to comment on availability/reliability, but what other company provides all this for USD $25.00 / month?
Here i wish to explain things a little.
there could be 1000s of hosting provider who may provide you hosting for installing and running magento but you need to take care of latency factor too, if your users and clients are based is US, consider having a magento hosting from USA based data-center like you may ask godaddy for this but now as it is the fact that online shopping is being processed through out the world so countries like Pakistan i will recomend WinsHosting who is renowned due to their most convenient php hosting for installing any open source script quite smoothly.
You can find their all hosting plans here: Magento Hosting provider in Pakistan
Based on your budget and size, I would recommend one of the smaller all-in Magento hosts like Nexcess. If you don't have any technical folks on your teams that understand Infrastructure, there are other aspects to consider as you grow. Cloud hosting with AWS/Google and a strong partner there like Webscale can make your life easier. The spend is also a bit more but it eliminates tech spend and helps with site performance, fine tuning and checkout success.