attributes as a textbox auto selecting correct price

[jimbeeer]

My client needs his product attributes as a textbox. But here's the catch, it needs to select the appropriate price automatically.

 

E.g.

300 - 450 (£0.00)

451 - 600 (+£2.00)

601 - 800 (+£4.00)

 

The attributes above are already in the admin section but the client is insistent that he wants his customers to be able to type in '460' into the product attribute and it to automatically recognise that it's between the 451 - 600 range. If i had written this cart myself from the beginning i may have stood a chance sorting this out but as i haven't, i don't have the foggiest clue on how to do this.

 

The only way i can think of is i add the 'Product Attributes - Option Type Feature' and put in a text box, possibly to appear after the client selects one from the dropdown asking for them to type in the exact amount they want. Not ideal by a long shot but the only way i can think of.

 

Any help would be immensely appreciated!

 

-James