Your money may be worth more money than you think.

Even a dollar bill could be worth enough to pay some of those monthly bills.

The key is the eight-digit serial number, and whether it seems 'fancy' or special to collectors.

When the redesigned $100 bill comes out Oct. 8, the one with the serial number 00000001 could be worth $10,000 to $15,000, Dustin Johnston, director of currency for Heritage Auctions in Dallas, told the Boston Globe.

But, history aside, it's mostly about number patterns. Even $1, $2 and $5 bills can be worth many face value, according to collector Dave Undis of

A check of eBay shows examples, like a $1 bill fetching $86 for having the serial number 67676767, or another selling for $66.66 for having the number 00023000.

Patterns to look for include solid (every digit the same), such as 11111111; ladder (counting up or down), such as 12345678; low, 00000100 or lower;  high, 99999900 or higher; radar (same backwards and forwards), such as 13466431; repeater (second half same as first half), such as 12791279; super repeater (pair of numbers repeated four times), like the first eBay example above; double quad, such as 55553333, seven in a row and seven of a kind.

Dates can also be collectible, such as 07041776 and 09112001, owned by one collector, the Globe notes. Nonhistoric dates could also be valuable, like 04171982 – if you can find someone with that birthday or anniversary.

The "For sale" list at Undis' website asks $4000 for a 2006 $1 bill with 11111111, $750 for a 1935 $1 bill with the number 00000011, and $750 for a 1935 $1 bill with 19999999, to cite some of the pricier examples. Dozens are listed at under $100.

"The prices on my web site are representative of the current market," he emailed.

Higher asking prices can be found on eBay, like $9,999 for a 1928 $50 bill with the serial number 00009999. The seller has already rejected five offers.

The ceiling is much, much higher.

Royersford, Pa., dealer Billy Baeder has a $10 bill with the serial number A00000001A that he believes is worth $500,000 because it's a rare 1933 Silver Certificate.

See: Royersford man has a $10 bill worth $500,000?

Anyone finding a fancy serial number has a variety of options.

Besides Cool Serial Numbers, dealers who specialize in such bills include Baeder's USA RareExecutive Currency,  , and Tickle Your Fancy Currency.

In addition to eBay, Undis says, "currency auction houses are also good, especially for the more valuable notes. My favorites are Heritage Auctions and Lyn Knight Auctions."

He also has a "wanted" list of bills he's looking to buy.

Kind of gives the ad slogan, "What's in your wallet?" a whole new meaning.

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