Sorry if I write in Euro, but you can certainly do the maths:
1x 1m Low-Cost dish = 40 Euro
1x Ku-Band LNB = 10 Euro
1x DiSEqC-1.2 motor = 80 Euro
1x Linux Receiver = 250 Euro
1x 100m Coax Cable = 20 Euro
Total cost = 400 Euro
If you want it to be slightly better:
1) Use a 1.2m ALUMINIUM dish (bigger but lighter than steel dish)
2) Better Linux Receiver like VU+ Duo or 4K
Add to this the installation. No idea how much it costs, but setup and fine tuning can easily take half a day by an experienced installer.
Do it yourself with a friend and it takes 1-2 days without proper tools like satellite meter, but is fun and rewarding.
If you want to hunt for feeds, consider buying a CrazyScan-compatible SAT-Card for the PC. This can cost from 40 Euro to 400 Euro, depending if PCI or PCI-e, where you buy it, new or second hand, etc. Google CrazyScan and EBSPro.
DiSEqC-1.2 motors are self contained and work with any modern receiver. They are maintenance-free and will last 5-10 years. Then you will start having issues with oxidation and possibly internal failure. The only maintenance required eventually is realignment after a storm.
Regarding the SAT vs Internet question: you can actually stream most bouquets through ILLEGAL subscriptions. I never used them, so I don't know (nor am I interested) how good they work. Regarding LEGAL streams, they are quite rare due to copyright issues: most TV channels will only stream within the region they broadcast, as this is the region they bought the transmission rights for.
Is it worth spending 400-500 Euro in a satellite reception system? It depends what you want to achive:
1) You want to watch many channels in your native language in a legal way --> get an official subscription (in your case I guess that would be Sky)
2) You want to watch exotic channels to have a glimpse of what is going on in the world, even if you don't understand what they are saying --> get a satellite dish as described above
3) You don't care about legal stuff and are fine with copyright infringement: in that case you would use Bittorrent to download movies and series and get an IPTV subscription. This is illegal and you risk getting caught, with all consequences.
Regards,
Vitor