Filer/Search: Number is greater than..

Hello.

I have one number in custom field in each post and I need a special search:

For example:

I have this data in custom fields:

Post #1: 50 000
Post #2: 10 000
Post #3: 80 000

On the web is form: Insert the number, so you type “26 000” and hit enter

Now I need to show only the posts which have the number greater than “26 000”, so Post #1 & #3.

Is there any plugin or hack for this? Thank you for any help!