In 10/11, Chelsea brought in Torres (58,5), Luiz (25) and Ramires (22) along with Benayoun (7) and Kalas (6) to a side that was already quite good, having won the title in 09/10.
In 06/07, the title winning side of 05/06 added Shevchenko (43,3), Mikel (20), Boulahrouz (13,2), A. Cole (7,4) and Kalou (4).
Given today's price inflation, I'd say those summers are similar to our current one. Plus, your side was better, relatively speaking, than our current side. Thus, summers like this have been seen before.