I need to find a US registered patent agent/agency able to help in
revising the patentability of a provisional patent application for a
bussiness method. Fees need to be in the low range (as a matter of
fact, as low as possible!).
The patentability assessment should include suggestions to improve the claims.

Tateti,
You might check this site's explanation of what can be patented.  I
have difficulty understanding how a "business method" meets the
description:
http://www.silo.lib.ia.us/specialized-services/patents-trademark/patent-definition.htm

Good luck, Myoarin

Dear Myoarin,
Thanks a lot for your message!
Best regards,
Tateti

Yes, Business Method patents are available in the US.  The State
Street Bank & Trust Co. v. Signal Financial Group, Inc. 149 F.3d 1368
(Fed. Cir. 1998) cert denied 119 S. Ct. 851 (1999) decision is the
ruling authority.  The most famous and controversial patent of this
type is the Amazon "1-click" patent.

Socal,
Thanks for the reference.  It is apparent that we need to know more
about the ?business method? to comment appropriately.  On this site,
the case report, footnote no. 2 makes just this point:
?[2] The use of means-plus-function language results in construction
of the claim as an apparatus (i.e., machine) rather than a method
(i.e., process), even if no discrete devices or structures are
described in the claim itself. See 35 U.S.C. § 112, para. 6. Structure
is imparted to the apparatus claims by reference to devices or
apparatus disclosed in the specification. See In re Donaldson Co., 16
F.3d 1189, 1192-94 (Fed. Cir. 1994) (en banc).?
http://www.kuesterlaw.com/saris.htm

As I understand it, Signature defended successfully its standpoint
that it had patented an ?apparatus? and not just a ?method (i.e.,
process)?.
Let?s not argue about it.  Savvy lawyers apparently haven?t been sure.
I hope this is of interest to Tateti.
Regards, Myoarin

myoarin-ga,

Business methods have been patentable for about a decade now, and are
rather well-known (infamous, even) and well-established.  There's
nothing to 'argue' about.  Quite a number of GA questions have
addressed these sorts of patents.

Paf, thanks.
Perhaps I have (had) a too European concept of what a "business method" is.

http://www.intellectual-property.gov.uk/faq/patents/business_methods.htm

Apparently the term now (in the context of the question) implies the
necessary related technology:

"III. CLASS 705 - DEFINITION

The title of Class 705 is "Data processing: financial, business
practice, management, or cost/price determination." The definition of
Class 705 is "machines and methods for performing data processing or
calculation operations in the: 1) practice, administration or
management of an enterprise; 2) processing of financial data; or 3)
determination of the charge for goods or services.

Thus, only computer-implemented processes related to e-commerce, the
Internet and data processing involving finance, business practices,
management or cost/price determination are classified in Class 705. 
All other applications that may be labeled a "business method-type
application" will be classified, assigned and examined according to
their technology."

(Successfully Preparing and Prosecuting a Business Method Patent Application )
http://www.uspto.gov/web/menu/pbmethod/

Tateti,  
This site could be of help to you; the quotation is from a linked 13
page article.  There are several other links about Class 705.

Again, thanks, Paf.  I should have done more searching before.
Myoarin

Myoarin, thanks a lot for your post.
Pafalafa, thank you for your comment. I will have a look.
Socal, once again, thank you very much.

: )

Tateti