The whole raison d'etre of sniping is to try and win an item for a lower price than you could achieve through regular bidding.
except ebays built in autobid ALREADY DOES THIS.
let me explain this by a couple examples...
item is at $1
guy 1: bids $20 - you are the highest bid
guy 2: puts in autobid amount for $100
ebay: put guy 2's bid at $21
guy 1: bids $40
ebay: immediately comes back with an you've been outbid and the current bid is $41
guy1: bids $75
ebay: immediately comes back with an you've been outbid and the current bid is $72
guy 1: bids $120 - you are the highest bid.
no propose the next example
item is $1
Guy 1: puts in autobid for $100
ebay: guy 1 bids is at $1
grassniper: i'll pay upto $75 for this item
ebay:bidding ends in 5...4...3...
grassniper: $2
ebay: immediately comes back with an you've been outbid and the current bid is $3
grassniper: $4
ebay: immediately comes back with an you've been outbid and the current bid is $5
grassniper: $6
ebay: immediately comes back with an you've been outbid and the current bid is $7
grassniper: $8
ebay: immediately comes back with an you've been outbid and the current bid is $9
grassniper: $10
ebay: immediately comes back with an you've been outbid and the current bid is $11
grassniper: $12
...
...
...
ebay: immediately comes back with an you've been outbid and the current bid is $74
grassniper: $75
ebay: immediately comes back with an you've been outbid and the current bid is $76
grassniper: okay
ebay: the auction has ended
or
Guy 1: puts in autobid for $100
item cost $1
current bid is $1
grassniper: puts in auto bid for $150
ebay: immediately comes back with your current bid is $101
5...4...3...2...1
the auction has ended and you pay $101
any way you look at it, the outcome is the same. you get the item for the lowest price within the budget you specified. you can snipe with autobid, you just need to go just before it ends and setup an autobid for the item with your budget.