I'm planning to cycle from Amsterdam to Budapest in September. I only have a high end Road bike which is not suitable for the trip. My idea is to buy a tourer or mtb in Amsterdam then take it back home to Dubai and sell it after the trip. I'm finding it difficult to find cycle shops online that have the kind of machine I need. Budget is up to 1200 euros. Can anyone suggest a good shop so that I can pre arrange this before I land into Amsterdam.
With new bikes in the heigher end of budget you will need to order a bike before you arrive and have it prepared for you. Most bike shops will need a few days to a few weeks to order and prepare your bike, depending on the kind of bike and the speed the factory delivers. Cheaper bikes are often more readily available from shops that just stock on spec, but those are likely not what you want for a long bicycle holiday.
Second hand bikes might be an option, but most of those are not advertized and anyhow you will need to fit and search till you get the one that suits you.
In that case I would suggest a week or so where you can visit several bike shops that have a good collection of second hand bikes.
I would suggest an online search for tweedehands fietsenwinkel Amsterdam which means 'second hand bike shop Amsterdam' and which will give you a sense of how many shops there are.
But it is likely better to buy a bike at home if you can transport it, as you will have time to check bikes out and get one that suits you best.