At today's difficulty (if you could buy your equipment and get it running before the next difficulty change), you would need about 4.642 terahash per second to generate 0.05 BTC per day. However, difficulty is still rising, so in a few weeks, that won't be sufficient any longer. If you want to still be generating 0.05 BTC in 6 months, then you should plan on about double that. So, you probably want about 9.284 terahash per second.
I'm no expert in mining, but the fastest miner I'm aware of right now is the "
Spondooliestech SP35 Yukon" at 5.5 terahash per second. Their website indicates that you can purchase this unit for about $2235, but it is currently out of stock. You'll either have to wait until there are more available (by which time the difficulty will have increased), or you'll need to buy one from someone that managed to get one before they ran out (in which case you'll probably pay more than $2235).
According to the specs, that equipment uses 3.65 kilowatts of electricity (which works out to about 87.6 kilowatt-hours per day). You'll have to take a look at your electricity rates. My average rate is about $0.11 per kilowatt-hour. So it would cost me about $9.64 per day in electricity to run the equipment.
Keep in mind that if you have any interruptions (power outages, equipment failures, internet outages, etc) then you will not generate any bitcoins during the downtime, and the difficulty may be higher by the time you get the equipment back online.
So, for approximately $2200 (plus $9.62 per day) you get to generate about $12.50 worth of bitcoins per day.
For that same $2200, you could just purchase more than 8.8 bitcoins today (instead of mining them slowly over then next few months), and purchase an additional 0.04 BTC per day with the $9.64 that you would avoid spending on electricity.
Are you sure that mining is the best way for you to acquire the bitcoins that you want?
