Of course there are cheap paintball markers. But the same applies to paintball: if you buy cheap, you buy twice.
A paintball marker must meet a certain standard in order to be allowed in Germany at all. Germany has very strict gun laws. According to the law, a paintball marker in Germany is a free weapon, which must always be marked by an F in a 5-corner. If this is missing, it is an illegal weapon. So stay away from imports from other countries. Not only do customs take their toll, you get an arms deal and the marker is gone. The security question would thus be answered.
Of course, there are big differences when it comes to longevity. A marker in the 100 euro range is not as durable as a higher-priced model in the 500 – 1000 euro range. If you only play 1-3 times a year, one marker is easily enough. If it is in the direction of 1 – 3 times a month, you should get good advice. Many manufacturers advertise in the low price segment with a lot of bling bling. Most of the time, however, these markers are not made very carefully.
If you want quality, you have to pay a price for it. Just like any other hobby.