Let me re-do the formula, including the other 15% I left out before.

Of monthly income:

-35% -> housing (mortgage, rent)
-25% -> transportation (car payment, gas, etc)
-15% -> yourself (fun, entertainment, etc)
-15% -> bills
-10% -> savings

On a $30,000 FO salary, with taxes taken out, it gives you roughly +/-

1) >$650 for housing
2) >$460 for transportation
3) >$280 for yourself
4) >$280 for bills (cell phone, etc)
5) >$180 for savings

*Edit: At ASA, for example, second year pay is $34/hr. Assuming 1,000 hrs. per year, which is what is usually used to calculate pay, gives you roughly $34,000 for the year. Taking out taxes, thats over $740 for housing, over $530 for car/gas, about $318 for yourself, $318 for bills, and $212 to save, which is over $2,500 in savings for the year. $740 gets you a pretty nice apartment. Lets say you spend $50 per week ($200/month) to fill your car with gas, which is probably on the higher end, unless you have a big SUV, that is $330 for a car payment, which is a nice car. You can still live a good life on FO salary, just live within your means. That is the point.

Lets say you become a captain after your fourth year as an FO, at ExpressJet. $64/hr, flying 1,000 hrs per year. Roughly $64,000 per year, +/-. Lets also assume you are married, and your wife makes at least $30,000.
That is a total income of $90,000, which gives you;

1) >$1,900 for housing
2) >$1,400 for transportation. (If you both have a vehicle that costs $50 a week to fill up, which is probably not the case for most cars, that still leaves over $1,000, or $500 each for a car payment, which is a nice car for both of you)
3) >$800 for yourself
4) >$800 for bills
5) >$500 for savings, which is nearly $7,000 in savings for the year.

Since commuting does cost extra, unless you have a reason you need, or have to live away from base, as an FO, it probably makes more sense to find a place to live at your base. Wait and commute, if you want to, after you have upgraded to captain, and have more money to put toward commuting. As an FO, your money is more limited, thus it is better not to have extra expenses where not necessary.

As you can see, it certainly does not take 5 other FOs splitting a one bedroom apt. to make it as an FO. Initially, first year, you can easily survive by just getting together with another FO during training, and you two split the rent of a two bedroom. After first year, I don't see a major need for a roommate, with most regionals, unless you just enjoy the company, and splitting of the costs. I know plenty of people who have made it fine on there own with less than FO regional pay. It can be done!