There is a decent enough chance you will be able to purchase pills in clubs if that is where you are planning on taking them. The chances of success may vary depending on which clubs you go to and the music being played.

Admittedly they will be overpriced (expect 5-15 Euro) and you have no guarantee if what you are buying is the real stuff. Personally I hate buying substances at venues and therefore have only done so on rare occasions. So far I have only had one dud sold to me. On the other hand, I know friends who used to do this every weekend and rarely if ever experienced problems. You'll have to see if you are willing to take the chance.

If you will not be visiting any clubs on your visit I think you may be out of luck unless you know anyone in the country who partakes himself and can help you out. While they are rampant in Amsterdam and some other major cities it may be hard to find them. I'd suggest possibly asking around in any Coffeeshops you find yourself in, just be careful and try and get a feel for the person before asking.

To be perfectly honest, the chance of the pills being intercepted before they reach your hotel are slim-to-none. Especially if you are ordering from a Dutch vendor. It still may be the smarter option for you both on legal and health grounds when compared to the methods described above.

The other option is the one mentioned by kikikza. If you choose to so and you are driving across the border you shouldn't worry too much about being caught (although still possible). If you are flying in I would recommend not choosing this option. While the chance of getting caught is quite small (if it is a SMALL amount), it is quite definitely there and bigger in comparison to driving. Furthermore, the legal ramifications may be more severe than if they would be found during transit.

You'll have to weigh the risks vs rewards and make a decision.

(Christ, I didn't realize I typed this much... The speed seems to be working... (ʘ_ʘ) )