Who knows GPS antennas?

I have been looking online but there seems to be, for a lot of the antennas, an assumption of prior knowledge. That I don't have. What I want to do is survey some of my property line. Mainly so I know about where it is because about 25% of the length is ambiguous. I can pay a surveyor to do the job but it would cost about 4 thousand bucks. Of course a proper survey would be more accurate and precise but I don't need that accuracy or precision. So I am looking for an antenna that could be either plugged into a handheld GPS or a tablet. And I don't know even where to start. I don't know how much gain I need. Or sensitivity. Maybe there is already a han held unit that is good enough all by itself. Our property is heavily wooded with a mix of conifers and deciduous trees, mostly alders. In the summer the trees make my hand held GPS unit useless. It is an older unit so I will be buying a modern one that will hopefully be better. I live north of Seattle and the satellites seem to be mostly in the southern sky, if that makes any difference to any antennas. I would like to keep the total expenditure for antenna and GPS unit to less than $400.00 I have looked into renting a surveyors GPS unit but have not been able to find anyone in the greater area who rents them. Can anybody help? Thanks, Eric