It appears so. See The Unreformed House of Commons: Parliamentary Representation before 1832 (1903), by Edward Porritt, for a discussion on this. On page 357-358:
"It was in this period when, as the North correspondence shows, a nomination to a seat fetched from two thousand five hundred to three thousand pounds, that seats were first advertised for sale the London newspapers. Nominations at Honiton, Milborne-Port, and Reading, were offered in the London Chronicle of December 26th and 29th, 1767, and in the Gazetteer and New Daily Advertiser of February 4th, 1768. The boroughs were not named. It was merely stated that there were for sale 'some boroughs which would come reasonable,' and that inquiries respecting them could be addressed to the printers. These advertisements of 1767 and 1768 brought the printers into conflict with the House Commons on a question of privilege. But advertisements offering boroughs for sale, and advertisements of men seeking nominations for boroughs continued to appear at general elections until as late as 1807, the last general election preceding the Act of 1809, which made the sale of seats illegal."
The page cites the Morning Chronicle, May 4 and 21, 1807, and Morning Post, May 21 1807, as also running these ads.
If I can find one of the actual ads, I'll add it to this answer.
Edited to add:
I've found a later interesting reference in the 15 August 1835 issue of The Spectator:
"IF seats in the House of Commons can be purchased now in the same manner as under the old system, we presume that no person, professing to be a Reformer, will maintain that the Act of 1832 ought to be a final measure. Well, what is the fact? A seat in Parliament has been publicly offered for sale within the present week, by a solicitor of Gray's Inn. The Courier of Wednesday contains the following advertisement.
"'SEAT IN PARLIAMENT.—To be disposed of, a property which commands influence sufficient to return a Member. Apply personally to Mr. Witham, solicitor, No. 8, Gray's Inn Square, London ; if by letter, to be post paid.'"
Aha, here's the actual ad in The Courier, 12 August, 1835: