Metal alloys properties?

Hi so I was looking for a BMX bike and I discovered a lot of alloys I never heard of before.Basically what I'm asking is if anyone could sort them first by weight/volume ratio (from the heaviest to the lightest) and then by overall strength/volume (from the weakest to the hardest) and by cost.The alloys are: Hi-Ten steel (a mixture of steel and carbon I suppose),Cr-Mo steel 4130 (steel + chrome + molybdeum and some carbon I think),Aluminium alloy 6061 (aluminium + magnesium + silicon),magnesium alloy (I don't exactly know what alloy they could be using for bikes,anyone can enlighten me here?) and titanium alloy (again I do now know what alloy they could be using for bikes..) For exact percentage please search on wikipedia.. thanks guys I'm asking this just because I'm curious I don't have enough money to buy anything better than Cr-Mo steel so I'm just asking thanks!