I also heard that mining litecoins, dogecoins and other scrypt coins will make your profit since you can mine a substantial of them in a short time and are not worth alot, but if the value of one goes up, profit will occur. Should I buy a Mining rig for bitcoins(SHA-256) or Dogecoin/litcoin (Scrypt)?
Assuming that you are mining for a profit (vs just a hobby or experiment) and that you are not getting "free" power from your mom's garage or something, then what you heard is obsolete. It was only valid until the moment when it became CHEAPER for the "home miner" to buy coins on the market rather to mine them.
Let's assume that you have $230 to invest right now. Buy 1 BTC with them. If BTC price goes up 10x, then you'll have made $2,300 with your $230 investment.
If you buy mining gear instead, and take let's say half of it ($130) for the hardware, and the other half for electricity, then you will never be able to make anything even *close* to 1 BTC (guessing at most 0.2-0.3 BTC right now). Again, if BTC goes up 10x, then you will only have made $460-$690 with your initial $230 investment, instead of $2,300 with the buying BTC option.
EDIT: the same goes for scrypt coins, AFAIK it's even worse. And be careful with altcoins, they carry BTC instability + their own...