Without mailing tube and postage, 450 would cover the prints.
Unfortunately, for the home printer like me, the 15 per linear feet is what it costs to print.
To get "perfect" prints worth their money usually involves a minimum number of 2 or 3 prints to make sure the colors are correct (sometimes get it in one print proof, but is rare), and that's not taking into consideration that when printing anything, one small thing can go wrong and the print is ruined, so commercial shops usually double the print cost to pad the losses that will happen.
Anyways, the rule of thumb on this kind of printing is to double the cost to print to make up for the inevitable wasted ink & paper it almost always takes to set up a big print.
I haven't even turned my printer on in two years. Just the head cleaning cycle it goes through when turned on uses about $13 worth of ink.
If you really want some poster action, you might be better jobbing it out locally.
A commercial shop will be able to offer you a better deal than I could.
One with an Epson 7800 or bigger, or Canon or HP also have similar printers, but Epson is the best when it comes to image quality on the large format printers.
If the creator of the logo used Illustrator or another vector-based art program, you could get a copy of the file and get it printed out as big as you could afford with no loss of quality.
If it was created as a bitmap image, you'll need as large a version of it as you can get (or re-make) if you want a poster that's worth your time & money.
