...... at the top of this page and you will find 100 posts.
Not all are relevant, but many are.
From your interests I would say a modest to midrange spec bought as a ready built box is all you need.
The top of the range products are for those with no spending limits, who must_have one because it is the most expensive and elaborate.
Nearly all the current sales are of high specification. The cost difference being extra RAM, high performance graphics cards and fancy CPUs which are often capable of more than current software can use.
Within your price you could go for 2Gb RAM and even a decent TFT monitor as well.
Don't forget the OS which is often available as an extra in case you already have one to install.
Two online suppliers which have own build offers and a good support reputation, are Novatech and Dell.