You would have to spend quite a bit of money to get speakers that will match a decent set of headphones, such as the 595, almost certainly more than the price you're looking at unless you find some absolutely killer deal.
The real question, as YYHDJ said, is can you handle listening to headphones instead? If you've always got sound being output then chances are you might get a little tired of listening to headphones after many hours (depending on which ones, the lenght of time will vary). In fact, because some headphones are so good a reproducing sound that you will get tired listening because you're brain is processing all of the detail. This is also dependent on several factors (such as type of music you listen to), so there's not realy way to say how long you might be able to listen to them before you get tired. A lot of lower end speakers are aimed at producing typical sound that people hear well, but not be overly great at actually reproducing the sound (so they're made to sound good with what people typically listen to, and not designed for accuracy, not that the two are necessarily mutually exclusive), whereas headphones such as the 595s are designed more with clarity and detail and other technical capabilities (again, not to say they sound bad at all).
I had the HD-280s and agree with YYHDJ that after a while you just feel like you need to take them off. The HD-595s are quite a bit more comfortable, and I don't ever recall having them on for a long enough period that I felt like I needed to stop listening.
Also, for gaming, I know a lot of people seem to prefer headphones, especially when paired with an X-Fi. The only thing you really lose is the thump of a subwoofer, which if you weren't going to buy one anyways is kinda null point. Headphones can do an excellent job with bass, but they can't replace the feel of a sub.
If I was going to go the reciever route, I would want to pair it with a card that does Dolby Digital Live and/or DTS Connect encoding, and would want surround sound and a nice sub. But that's just me. If I was aiming for only 2 channel I would be looking more at headphones.
I can't say for sure for where you live, but over here in the US its not too difficult to find a pair of bookshelf speakers that sound pretty good for around $100-150, but headphones will beat them in quality quite easily.
Oh, and one last thing, for your uses, I would also look into the Audio Technica ATH-A900s, I compared them directly to the HD595s and felt they just sounded so much better. A lot of Head-fier's agree that they make a better all around gaming/music headphone, but it will depend on you liking one's sound versus the others, as they both sound good. They're also more comfortable than the 595s in my opinion.
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