I will appreciate if any experience hand can avail me the cost of developing a website for a steel construction company,
I need the cost of registring the domain, hosting, also how i can integrate online payment system to the site.
Pls kindly let me know the most reliable payment merchant in nigeria and their charges.

pls this information is urgently needed.

One task at a time. First of all, what is your experience, do you plan on doing this yourself, or do you want someone to do the whole thing, and you are trying to find out how much tat will be? What kind of functionality do you want, what kind of data/entity do you need information about, etc? If you do not have all this information handy, and you want someone to come in and do the analysis/design and development, then that will all need to be factored into the cost. Seriously, it's not easy to just give you a ballpark figure without knowing more from your end.