Okay, let's take a look at your code:
I suspect that your understanding of regex is what's at fault (the reliance on (.*) gives that away!) but, the [u] makes me think that you want to have '[u]' IN your URL - it won't happen! Have a look at http://www.ietf.org/rfc/rfc2396.txt which will show you which characters are allowed in a URL and under what conditions.
RewriteRule (.*)/([A-Za-z]*[u])/$ /details.php\?z\=$1\&w\=$2 [L]
# That says to CAPTURE everything before a /,
# then CAPTURE zero or more uppercase or lowercase letters
# followed by a u (the square brackets aren't needed)
# and a / to terminate the string - too weird for me!
# The redirection does not use the atom created
# by the regex and should NOT have the \'s
# The [L] was added to TERMINATE the block statement
# so it's not ANDed with the next block statement
RewriteRule (.*)/([A-Za-z]*[u])$ /details.php\?z\=$1\&w\=$2
RewriteRule page(.*)/cost(.*)-(.*)/(.*)$ index\.php\?curpage\=$1\&p\=$2\&costy\=$3\&t\=$4
# ARGH! The same thing as above but then ANDed with
# another RewriteRule which must match page, ANYTHING/NOTHING,
# a /cost, another ANYTHING/NOTHING, a dash, a third
# ANYTHING/NOTHING, another / then ANYTHING/NOTHING and
# redirect to ... it doesn't matter 'cause it'll NEVER match after
# the prior redirection.
RewriteRule (.*)/([A-Za-z]*[u])/$ /details.php\?z\=pleaseReturnaVariable
# Ditto the first explanation including the \'s in the redirection
# and the lack of definition of pleaseReturnaVariable