Mattock and Delph are 2 young cheap players you should bring in.Delph is more of a low-mid table player in the prem i think but Mattock is a amazing LB.Still Delph is very cheap for his quality and give him 1-2 seasons you will make a large profit on him.
Check the teams who were relegated from the prem for cheap buys.They may not be the best but as a newly promoted team you will never get the best anyway.Hull, Stoke, West Brom, Boro, West Ham are common teams to go down and all have a few players who could help you survive in the prem.
Depending on your money you can pick up fringe players from the top teams who can really shine.Evans and Sturridge from Man City, Vaughan from Everton rarely break into the first team in the first few seasons and even if your low on cash Sturridge and Evans can be loaned quite often not sure about Vaughan as i never tried to loan him.Fleck may join you if you have the cash to pay for him but hes not normally cheap but worth it if you can afford him.
Try pick up some old timers too they may not have much left in them but more than enough to keep you up for the first season.Check those who are out of contract you could hit up on a solid player or 2 just to get you through what is gonna be a hard season.