Ignoring the Target Blue variant, this was the first issue in the Ultimate series which sought to modernise the Marvel comic book world and by 2004 it was exceeding the sales of the
legendary Amazing Spider-Man title (which started in March 1963).
A large number of variant editions exist for this first issue with the top two being the white, 1:100 ratio, retailer incentive cover and the Dynamic Forces cover
variant which was limited to 5,000 copies. There is also the "Target Blue" edition but this is a reprint of issues #14 and #15 hence is not the same content or release date
(not a true variant!).
Below is a high grade CGC encapsulated signature series copy:
CGC graded 9.8 white cover variants were making anything from $400 to $650 in mid 2013.