I have an extremely secure version of a script for this all ready, can be transferred to you instantly, and minimal effort would be required to make any desired changes.
Days to deliver is taking into account a couple of days for making any adjustments to the system you want, although I could provide the basic login, register and lost password immediately if you wish.
It's important to consider the security of such a script, as with logins, if the security is low, the site can be compromised with ease, and your login is pointless. I offer absolute security against cross-site scripting, SQL injection, and much more.
My script will make it easy to customise the appearance of your login form, and will allow other coders to easily expand on my code, cleanly integrate it into a website, and much more.