The amount you pay for your deal is going to be the largest chunk of money that goes into your rehab budget. You always want to pay the lowest price possible and you may need to negotiate your butt off to get it. So you need to have good motivation and business skills to get that property as low as possible. The higher the cost you have to pay to buy the property the more you have to pay back from your final sale price.
And that makes no difference whether you are paying the amount yourself or if you are going through a lender. If you go through a lender, you will have pay back not only the initial amount of the purchase price, but one or both of interest on that loan or profit spread between the loan amount and the split of the final profit value. If you pay for the property from your own money, then you lose interest on that money until you are able to sell the property and pay yourself back. Plus using your own money may mean that you will have less money to use for repairs and renovations, which if what is needed is not taken care of to make the property the best it can be, you will not get anywhere close to market value for it.
You need to do your best to pay only the lowest possible price you can for your property. Deal, negotiate, entice the seller with something of added value in the vein of “you scratch my back, I’ll scratch yours.” Whatever you can do to get that property as low as you can is money in your pocket.