The Hammers were one of the busiest clubs in the summer, signing 12 players in total with a net spend of around £25-30 million including loan fees.
The east Londoners are widely considered to have done some of the best business of the summer overall.
Left-back Stephen Hendrie, goalkeeper Darren Randolph midfielders Pedro Obiang, Martin Samuelsen, Manuel Lanzini and Dimitri Payet and defensive reinforcements Angelo Ogbonna and Carl Jenkinson were all recruited over the summer.
Kings of deadline day
That was before a quite memorable deadline day in east London where no less than a further four players were brought in.
Hull City striker Nikica Jelavic, Barcelona midfielder Alex Song, Chelsea star Victor Moses and Nottingham Forest's exciting and powerful winger Michail Antonio all signed up as the deadline day headlines were dominated by the Hammers.
The former Croatia boss led his side to one of their best ever starts to a Premier League season and they were sitting just two points off the summit after 10 games.
Injuries hit progress
However, a glut of injuries have led to a run of six games without a win and the club has dropped to eighth as a result.
The Hammers remain just one win off fifth place, though, in this most open of Premier League seasons.
With long-term injuries to the likes of Payet, Sakho and Winston Reid and other key players like Lanzini and Moses also on the sidelines, many fans expect the club to bring in reinforcements in the winter window.
'We already overspent'
But responding to the question "Do we have a sizable budget for January?" on Twitter, Sullivan revealed a lack of money and quality players will put paid to any business next month.
"No the club is going to lose a lot of money this year. We overspent in the summer," Sullivan said on Twitter.
"Can you buy quality in January?"
No the clubs going to lose a lot of money this year. We over spent in the summer! https://t.co/ZugcKhGjlV— Jack Sullivan (@jsullivanwhu) December 15, 2015
Can you buy quality in January? https://t.co/DKarUoFpQE— Jack Sullivan (@jsullivanwhu) December 15, 2015
Reinforcements not necessary
Although the Hammers have not won in six, they have only lost two of those and been unlucky not to come away with six points from back-to-back 0-0 draws against Stoke City and Manchester United.
West Ham's injury situation also looks set to ease slightly after Enner Valencia returned to the bench for the 0-0 draw with Stoke last time out and Lanzini was tipped to be fit again for this weekend's game against Swansea, two weeks ahead of schedule.
With Payet also said to be ahead of schedule in his recovery from a three-month lay-off due to an ankle injury, by January Bilic may well have a number of selection headaches again.
So a lack of transfer budget for January could be a blessing in disguise as new faces may unsettle what is a healthy squad.