Integration with existing site

[BenBarbour]

I have a site that is designed with the following logic:

1) User accesses a PHP page that compiles necessary data needed for the page.
2) an HTML template is then parsed and the data (HTML code) is placed in the appropriate locations and the page is displayed to the user.

I like this program's look/feel but unfortunately the way it is coded I'm not sure I can use it with my existing site (due to the extensive use of the "echo" function).

Is there a way, assuming I purchase this, to return the HTML code as a string variable as opposed to including a PHP script that writes directly?

Thanks...