Pools are expensive; they just are. You are going to be tempted to skimp on this-and-that to save money. While you may be able to skimp on certain pool products, you can never skimp on pool equipment, primarily the pump and filter. While pool chemicals are always given sole credit for optimal water clarity and sole blame for unclear and otherwise distorted water, the main contributor to overall water clarity is actually circulation and filtration, which is controlled by the pump (circulation) and the filter (filtration) as well as the plumbing pipes.
Do not just buy a pump or a filter because of its cost. Rather, do some research to buy a properly-sized pump and filter. Having the correct pump and filter for your pool will make your pool maintenance requirements quicker and easier. The Pool Manual will provide all the information you need about pumps, filters, plumbing pipe sizes and schematics, flow rates, turnover rates, velocity rates, and other criteria for properly sizing pool equipment to the gallons of water in the pool and other pool specifications.
Too many pool owners have pools with improperly-sized equipment. For whatever reason, pumps are often over-sized (in terms of horsepower) while filters are too often under-sized (in terms of effective filtration area).
You can read the Pool Manual for additional information about pool equipment, pumps, filters, plumbing pipe sizes and schematics, and all the criteria to poperly-size the pool equipment and plumbing.