This will be my first domain, a 3 letter .net domain starting at 1200USD. Is there anything special I have to keep in mind while trying to buy it or is everything safe as long as I buy it through escrow.com?

If I invest like 1500USD in this, I should always be able to sell it for that in a few years, right? How far should I go, up to like 2000?

Speculating in domains has no guarantees. Same as speculating in the housing market, the stock market or Beanie Babies. In the long run they are likely to up in value but no guarantees. Whether the domain is worth $1200 or $2000 today would depend on the 3 letters or 3 characters.
Nets are not worth as much as coms and the chart (in the link) shows an average sale price of $400 for 3 letter nets in recent months while the table shows $825.
http://www.3character.com/3-letter-domain-name-sales-history.html
http://www.3character.com/priceguide.html
"Current Observed Minimum Wholesale Price (regardless of letter combo) as of November 1, 2007: * 3-Letter .com - $5500 (+ $550 since October 1, 2007 report)* 3-Letter .net - $825"

If I invest like 1500USD in this, I should always be able to sell it for that in a few years, right?
The short answer is NO, or EVERYBODY and his mother-in-law or even her dog will be buying up 3 letter .net's. Most people who LOSE in speculation tend to think JUST LIKE THAT.

I see. Well, the reason for buying this domain isn't actually to make any profit of it, but because of the name which I want and will keep using for the forseeable future.

The thing I'm afraid of is if I buy it for 1500 and then the internet chanegs somehow in a few years so that it won't be worth anything.

depending on the letters, if its any three letters its kinda higher than current market value

but if its a word like dad cat why ask .net might be a catch

This will be my first domain, a 3 letter .net domain starting at 1200USD. Is there anything special I have to keep in mind while trying to buy it or is everything safe as long as I buy it through escrow.com?

If I invest like 1500USD in this, I should always be able to sell it for that in a few years, right? How far should I go, up to like 2000?

Hi!

As there is not info provided therefore the only think which i can suggest is the domains are valuated on the amt of traffic it is getting, if you think that you can develop the domain well to enhance its worth then i don't think there would be any problem.

Regards,