There are lots of great routers for <$100, no need to wait. A-Power has this one on sale for $50 right now:
A-Power.com - Buy TP-Link TL-WR1043ND 4 Port Wireless N Gigabit Router 2.4GHZ 802.11 N/G/B 300MBPS #15925 - TL-WR1043ND - Canada
First thing you can do to secure your Siemens though, is change the admin password - it's "telus" by default and I have yet to come across one that the user has changed.
Once you have a new router, you should disable the wireless on the Siemens and set it to operate in bridged mode, thus disabling all the router functions, and make sure to change the admin password.